diff --git a/common/config/rush/pnpm-lock.yaml b/common/config/rush/pnpm-lock.yaml
index 8774d9a2b5..cedb0a1272 100644
--- a/common/config/rush/pnpm-lock.yaml
+++ b/common/config/rush/pnpm-lock.yaml
@@ -983,6 +983,9 @@ dependencies:
   minio:
     specifier: ^7.0.26
     version: 7.1.3
+  moment-timezone:
+    specifier: ^0.5.43
+    version: 0.5.43
   mongodb:
     specifier: ^4.11.0
     version: 4.17.1
@@ -13221,6 +13224,16 @@ packages:
     resolution: {integrity: sha512-ySViT69/76t8VhE1xXHK6Ch4NcDd26gx0MzKXLO+F7NOtnqH68d9zF94nT8ZWSxXh8ELOERsnJO/sWt1xZYw5A==}
     dev: false
 
+  /moment-timezone@0.5.43:
+    resolution: {integrity: sha512-72j3aNyuIsDxdF1i7CEgV2FfxM1r6aaqJyLB2vwb33mXYyoyLly+F1zbWqhA3/bVIoJ4szlUoMbUnVdid32NUQ==}
+    dependencies:
+      moment: 2.29.4
+    dev: false
+
+  /moment@2.29.4:
+    resolution: {integrity: sha512-5LC9SOxjSc2HF6vO2CyuTDNivEdoz2IvyJJGj6X8DJ0eFyfszE0QiEd+iXmBvUP3WHxSjFH/vIsA0EN00cgr8w==}
+    dev: false
+
   /mongodb-connection-string-url@2.6.0:
     resolution: {integrity: sha512-WvTZlI9ab0QYtTYnuMLgobULWhokRjtC7db9LtcVfJ+Hsnyr5eo6ZtNAt3Ly24XZScGMelOcGtm7lSn0332tPQ==}
     dependencies:
@@ -17768,7 +17781,7 @@ packages:
     dev: false
 
   file:projects/calendar-resources.tgz(@types/node@16.11.68)(esbuild@0.16.17)(postcss-load-config@4.0.1)(postcss@8.4.31)(ts-node@10.9.1):
-    resolution: {integrity: sha512-uhWVaA9LfyRGkkRYOipr4pcykZVqdl5EHUGCF146vAHuv01YV+njwZCeSRzbDYEB9VzQdPMdhh6/Wol8Zm3ENg==, tarball: file:projects/calendar-resources.tgz}
+    resolution: {integrity: sha512-GKA5RNUEh4K+pp2mAf479tKTKebnRqldRDNln/RgNekUVHs/vqOuzHbu/4uHlIpC1QJXxyi7H+m6lidp5bqv7A==, tarball: file:projects/calendar-resources.tgz}
     id: file:projects/calendar-resources.tgz
     name: '@rush-temp/calendar-resources'
     version: 0.0.0
@@ -17785,6 +17798,7 @@ packages:
       eslint-plugin-svelte3: 4.0.0(eslint@8.51.0)(svelte@3.55.1)
       fast-equals: 2.0.4
       jest: 29.7.0(@types/node@16.11.68)(ts-node@10.9.1)
+      moment-timezone: 0.5.43
       prettier: 3.1.0
       prettier-plugin-svelte: 3.1.0(prettier@3.1.0)(svelte@4.2.5)
       sass: 1.69.0
@@ -23711,7 +23725,7 @@ packages:
     dev: false
 
   file:projects/ui.tgz(@types/node@16.11.68)(esbuild@0.16.17)(postcss-load-config@4.0.1)(postcss@8.4.31)(ts-node@10.9.1):
-    resolution: {integrity: sha512-g5wJSxU0oHaWmOknjGHp3d+ML2V2bnveZV51xeHaq5GfbEwCdHat3DOsEt6zC3BMVRZsyJz8EmwNnd6A+KZYcA==, tarball: file:projects/ui.tgz}
+    resolution: {integrity: sha512-N7xpf37pbt76Fi7r6f4ioMRsUhBC6xMQmAliUP5wX0OLlzS/sU7SHQFqY5BYcXBV9HhyTcRqQ3cIG2yGgQivDQ==, tarball: file:projects/ui.tgz}
     id: file:projects/ui.tgz
     name: '@rush-temp/ui'
     version: 0.0.0
@@ -23731,6 +23745,7 @@ packages:
       fast-equals: 2.0.4
       jest: 29.7.0(@types/node@16.11.68)(ts-node@10.9.1)
       just-clone: 6.2.0
+      moment-timezone: 0.5.43
       prettier: 3.1.0
       prettier-plugin-svelte: 3.1.0(prettier@3.1.0)(svelte@4.2.5)
       sass: 1.69.0
diff --git a/models/calendar/src/index.ts b/models/calendar/src/index.ts
index 2d5809e048..ff790a1231 100644
--- a/models/calendar/src/index.ts
+++ b/models/calendar/src/index.ts
@@ -117,11 +117,14 @@ export class TEvent extends TAttachedDoc implements Event {
   access!: 'freeBusyReader' | 'reader' | 'writer' | 'owner'
 
   visibility?: Visibility
+
+  timeZone?: string
 }
 
 @Model(calendar.class.ReccuringEvent, calendar.class.Event)
 @UX(calendar.string.ReccuringEvent, calendar.icon.Calendar)
 export class TReccuringEvent extends TEvent implements ReccuringEvent {
+  declare timeZone: string
   rules!: RecurringRule[]
   exdate!: Timestamp[]
   rdate!: Timestamp[]
@@ -132,7 +135,6 @@ export class TReccuringEvent extends TEvent implements ReccuringEvent {
 @UX(calendar.string.Event, calendar.icon.Calendar)
 export class TReccuringInstance extends TReccuringEvent implements ReccuringInstance {
   recurringEventId!: Ref<ReccuringEvent>
-  declare originalStartTime: number
   isCancelled?: boolean
   virtual?: boolean
 }
diff --git a/models/calendar/src/migration.ts b/models/calendar/src/migration.ts
index 1667c5f062..948faa9e09 100644
--- a/models/calendar/src/migration.ts
+++ b/models/calendar/src/migration.ts
@@ -13,10 +13,15 @@
 // limitations under the License.
 //
 
-import { type Calendar, type Event, type ReccuringEvent } from '@hcengineering/calendar'
+import { calendarId, type Calendar, type Event, type ReccuringEvent } from '@hcengineering/calendar'
 import contact from '@hcengineering/contact'
-import core, { type Ref, TxOperations } from '@hcengineering/core'
-import { type MigrateOperation, type MigrationClient, type MigrationUpgradeClient } from '@hcengineering/model'
+import core, { TxOperations, type Ref } from '@hcengineering/core'
+import {
+  tryMigrate,
+  type MigrateOperation,
+  type MigrationClient,
+  type MigrationUpgradeClient
+} from '@hcengineering/model'
 import { DOMAIN_SPACE } from '@hcengineering/model-core'
 import { DOMAIN_SETTING } from '@hcengineering/model-setting'
 import { type Integration } from '@hcengineering/setting'
@@ -121,6 +126,17 @@ async function migrateSync (client: MigrationClient): Promise<void> {
   )
 }
 
+async function migrateTimezone (client: MigrationClient): Promise<void> {
+  await client.update(
+    DOMAIN_CALENDAR,
+    {
+      _class: { $in: [calendar.class.ReccuringEvent, calendar.class.ReccuringInstance] },
+      timeZone: { $exists: false }
+    },
+    { timeZone: 'Etc/GMT' }
+  )
+}
+
 export const calendarOperation: MigrateOperation = {
   async migrate (client: MigrationClient): Promise<void> {
     await fixEventDueDate(client)
@@ -128,6 +144,12 @@ export const calendarOperation: MigrateOperation = {
     await fillOriginalStartTime(client)
     await migrateSync(client)
     await migrateExternalCalendars(client)
+    await tryMigrate(client, calendarId, [
+      {
+        state: 'timezone',
+        func: migrateTimezone
+      }
+    ])
   },
   async upgrade (client: MigrationUpgradeClient): Promise<void> {
     const tx = new TxOperations(client, core.account.System)
diff --git a/packages/ui/package.json b/packages/ui/package.json
index 81163c9439..924de03b7a 100644
--- a/packages/ui/package.json
+++ b/packages/ui/package.json
@@ -43,7 +43,8 @@
     "svelte": "^4.2.5",
     "fast-equals": "^2.0.3",
     "autolinker": "4.0.0",
-    "emoji-regex": "^10.1.0"
+    "emoji-regex": "^10.1.0",
+    "moment-timezone": "^0.5.43"
   },
   "repository": "https://github.com/hcenginneing/anticrm",
   "publishConfig": {
diff --git a/packages/ui/src/components/internal/TimeZonesPopup.svelte b/packages/ui/src/components/TimeZonesPopup.svelte
similarity index 89%
rename from packages/ui/src/components/internal/TimeZonesPopup.svelte
rename to packages/ui/src/components/TimeZonesPopup.svelte
index 5b98380972..bb86106b3a 100644
--- a/packages/ui/src/components/internal/TimeZonesPopup.svelte
+++ b/packages/ui/src/components/TimeZonesPopup.svelte
@@ -27,7 +27,7 @@
     IconChevronDown,
     ActionIcon,
     IconUndo
-  } from '../..'
+  } from '..'
 
   interface TimeZoneGroup {
     continent: string
@@ -38,6 +38,7 @@
   export let timeZones: TimeZone[] = []
   export let count: number
   export let reset: string | null
+  export let withAdd: boolean = true
 
   const dispatch = createEventDispatcher()
 
@@ -142,18 +143,20 @@
                 {#each items as item}
                   <button class="menu-item no-focus items-center" on:click={() => dispatch('close', item.id)}>
                     <span class="overflow-label label flex-grow">{item.city}</span>
-                    <div class="tool ml-2">
-                      <Button
-                        icon={IconAdd}
-                        size={'small'}
-                        kind={'ghost'}
-                        disabled={count > 4}
-                        on:click={() => {
-                          count++
-                          dispatch('update', item.id)
-                        }}
-                      />
-                    </div>
+                    {#if withAdd}
+                      <div class="tool ml-2">
+                        <Button
+                          icon={IconAdd}
+                          size={'small'}
+                          kind={'ghost'}
+                          disabled={count > 4}
+                          on:click={() => {
+                            count++
+                            dispatch('update', item.id)
+                          }}
+                        />
+                      </div>
+                    {/if}
                   </button>
                 {/each}
               </div>
diff --git a/packages/ui/src/components/calendar/DateInputBox.svelte b/packages/ui/src/components/calendar/DateInputBox.svelte
index 95bbae4694..63c49b4528 100644
--- a/packages/ui/src/components/calendar/DateInputBox.svelte
+++ b/packages/ui/src/components/calendar/DateInputBox.svelte
@@ -18,11 +18,13 @@
   import Icon from '../Icon.svelte'
   import Label from '../Label.svelte'
   import IconClose from '../icons/Close.svelte'
-  import { daysInMonth } from './internal/DateUtils'
+  import { daysInMonth, getUserTimezone } from './internal/DateUtils'
+  import moment from 'moment-timezone'
 
   export let currentDate: Date | null
   export let withTime: boolean = false
   export let kind: 'default' | 'plain' = 'default'
+  export let timeZone: string = getUserTimezone()
 
   type TEdits = 'day' | 'month' | 'year' | 'hour' | 'min'
   interface IEdits {
@@ -44,19 +46,31 @@
     if (date == null) date = new Date()
     switch (id) {
       case 'day':
+        date = new Date(timeZone ? moment(date).tz(timeZone).date(val).valueOf() : moment(date).date(val).valueOf())
         date.setDate(val)
         break
       case 'month':
-        date.setMonth(val - 1)
+        date = new Date(
+          timeZone
+            ? moment(date)
+              .tz(timeZone)
+              .month(val + 1)
+              .valueOf()
+            : moment(date)
+              .month(val + 1)
+              .valueOf()
+        )
         break
       case 'year':
-        date.setFullYear(val)
+        date = new Date(timeZone ? moment(date).tz(timeZone).year(val).valueOf() : moment(date).year(val).valueOf())
         break
       case 'hour':
-        date.setHours(val)
+        date = new Date(timeZone ? moment(date).tz(timeZone).hours(val).valueOf() : moment(date).hours(val).valueOf())
         break
       case 'min':
-        date.setMinutes(val)
+        date = new Date(
+          timeZone ? moment(date).tz(timeZone).minutes(val).valueOf() : moment(date).minutes(val).valueOf()
+        )
         break
     }
     return date
@@ -81,15 +95,15 @@
   const getValue = (date: Date, id: TEdits): number => {
     switch (id) {
       case 'day':
-        return date.getDate()
+        return timeZone ? moment(date).tz(timeZone).date() : moment(date).date()
       case 'month':
-        return date.getMonth() + 1
+        return timeZone ? moment(date).tz(timeZone).month() + 1 : moment(date).month() + 1
       case 'year':
-        return date.getFullYear()
+        return timeZone ? moment(date).tz(timeZone).year() : moment(date).year()
       case 'hour':
-        return date.getHours()
+        return timeZone ? moment(date).tz(timeZone).hours() : moment(date).hours()
       case 'min':
-        return date.getMinutes()
+        return timeZone ? moment(date).tz(timeZone).minutes() : moment(date).minutes()
     }
   }
 
diff --git a/packages/ui/src/components/calendar/DatePopup.svelte b/packages/ui/src/components/calendar/DatePopup.svelte
index c64dae97b4..d0a3254752 100644
--- a/packages/ui/src/components/calendar/DatePopup.svelte
+++ b/packages/ui/src/components/calendar/DatePopup.svelte
@@ -19,11 +19,12 @@
   import {
     ActionIcon,
     Button,
-    Scroller,
-    deviceOptionsStore as deviceInfo,
-    checkAdaptiveMatching,
+    IconClose,
     Label,
-    IconClose
+    Scroller,
+    checkAdaptiveMatching,
+    deviceOptionsStore as deviceInfo,
+    getUserTimezone
   } from '../..'
   import ui from '../../plugin'
   import DateInputBox from './DateInputBox.svelte'
@@ -36,6 +37,7 @@
   export let label = currentDate != null ? ui.string.EditDueDate : ui.string.AddDueDate
   export let detail: IntlString | undefined = undefined
   export let noShift: boolean = false
+  export let timeZone: string = getUserTimezone()
 
   const dispatch = createEventDispatcher()
 
@@ -110,6 +112,7 @@
       bind:this={dateInput}
       bind:currentDate
       {withTime}
+      {timeZone}
       kind={'plain'}
       on:close={() => {
         closeDP(withTime)
@@ -126,6 +129,7 @@
           <MonthSquare
             bind:currentDate
             {viewDate}
+            {timeZone}
             {mondayStart}
             viewUpdate={false}
             hideNavigator={'all'}
@@ -140,6 +144,7 @@
               bind:currentDate
               viewDate={viewDateSec}
               {mondayStart}
+              {timeZone}
               viewUpdate={false}
               noPadding
               on:update={(result) => {
@@ -158,6 +163,7 @@
           bind:currentDate
           {viewDate}
           {mondayStart}
+          {timeZone}
           viewUpdate={false}
           hideNavigator={'all'}
           noPadding
@@ -169,6 +175,7 @@
           <div class="space" />
           <MonthSquare
             bind:currentDate
+            {timeZone}
             viewDate={viewDateSec}
             {mondayStart}
             viewUpdate={false}
diff --git a/packages/ui/src/components/calendar/Month.svelte b/packages/ui/src/components/calendar/Month.svelte
index 2c2d27bff2..6142cf3455 100644
--- a/packages/ui/src/components/calendar/Month.svelte
+++ b/packages/ui/src/components/calendar/Month.svelte
@@ -14,23 +14,26 @@
 -->
 <script lang="ts">
   import { afterUpdate, createEventDispatcher } from 'svelte'
-  import IconNavPrev from '../icons/NavPrev.svelte'
-  import IconNavNext from '../icons/NavNext.svelte'
-  import Icon from '../Icon.svelte'
-  import {
-    firstDay,
-    day,
-    getWeekDayName,
-    areDatesEqual,
-    getMonthName,
-    daysInMonth,
-    TCellStyle,
-    ICell
-  } from './internal/DateUtils'
   import { capitalizeFirstLetter } from '../../utils'
+  import Icon from '../Icon.svelte'
+  import IconNavNext from '../icons/NavNext.svelte'
+  import IconNavPrev from '../icons/NavPrev.svelte'
+  import {
+    ICell,
+    TCellStyle,
+    areDatesEqual,
+    day,
+    daysInMonth,
+    firstDay,
+    getMonthName,
+    getUserTimezone,
+    getWeekDayName
+  } from './internal/DateUtils'
+  import moment from 'moment-timezone'
 
   export let currentDate: Date | null
   export let mondayStart: boolean = true
+  export let timeZone: string = getUserTimezone()
   export let hideNavigator: boolean = false
 
   const dispatch = createEventDispatcher()
@@ -46,7 +49,16 @@
 
   let days: ICell[] = []
   const getDateStyle = (date: Date): TCellStyle => {
-    if (currentDate != null && areDatesEqual(currentDate, date)) return 'selected'
+    if (currentDate != null) {
+      const zonedTime = moment(currentDate).tz(timeZone)
+      if (
+        zonedTime.date() === date.getDate() &&
+        zonedTime.year() === date.getFullYear() &&
+        zonedTime.month() === date.getMonth()
+      ) {
+        return 'selected'
+      }
+    }
     return 'not-selected'
   }
   const renderCellStyles = (): void => {
diff --git a/packages/ui/src/components/calendar/MonthSquare.svelte b/packages/ui/src/components/calendar/MonthSquare.svelte
index b56724262d..ae9aaba50f 100644
--- a/packages/ui/src/components/calendar/MonthSquare.svelte
+++ b/packages/ui/src/components/calendar/MonthSquare.svelte
@@ -17,8 +17,18 @@
   import IconArrowLeft from '../icons/ArrowLeft.svelte'
   import IconArrowRight from '../icons/ArrowRight.svelte'
   import Button from '../Button.svelte'
-  import { firstDay, day, getWeekDayName, areDatesEqual, getMonthName, weekday, isWeekend } from './internal/DateUtils'
+  import {
+    firstDay,
+    day,
+    getWeekDayName,
+    areDatesEqual,
+    getMonthName,
+    weekday,
+    isWeekend,
+    getUserTimezone
+  } from './internal/DateUtils'
   import { capitalizeFirstLetter } from '../../utils'
+  import moment from 'moment-timezone'
 
   export let currentDate: Date | null
   export let viewDate: Date
@@ -27,6 +37,7 @@
   export let viewUpdate: boolean = true
   export let noPadding: boolean = false
   export let displayedWeeksCount = 6
+  export let timeZone: string = getUserTimezone()
   export let selectedTo: Date | null | undefined = undefined
 
   const dispatch = createEventDispatcher()
@@ -49,8 +60,26 @@
   }
 
   function isSelected (currentDate: Date | null, selectedTo: Date | null | undefined, target: Date): boolean {
-    if (currentDate != null && areDatesEqual(currentDate, target)) return true
-    if (selectedTo != null && areDatesEqual(selectedTo, target)) return true
+    if (currentDate != null) {
+      const zonedTime = moment(currentDate).tz(timeZone)
+      if (
+        zonedTime.date() === target.getDate() &&
+        zonedTime.year() === target.getFullYear() &&
+        zonedTime.month() === target.getMonth()
+      ) {
+        return true
+      }
+    }
+    if (selectedTo != null) {
+      const zonedTime = moment(selectedTo).tz(timeZone)
+      if (
+        zonedTime.date() === target.getDate() &&
+        zonedTime.year() === target.getFullYear() &&
+        zonedTime.month() === target.getMonth()
+      ) {
+        return true
+      }
+    }
     return false
   }
 
diff --git a/packages/ui/src/components/calendar/SimpleDatePopup.svelte b/packages/ui/src/components/calendar/SimpleDatePopup.svelte
index 702d615b31..9c2d1e3a7f 100644
--- a/packages/ui/src/components/calendar/SimpleDatePopup.svelte
+++ b/packages/ui/src/components/calendar/SimpleDatePopup.svelte
@@ -15,8 +15,10 @@
 <script lang="ts">
   import { createEventDispatcher } from 'svelte'
   import Month from './Month.svelte'
+  import { getUserTimezone } from './internal/DateUtils'
 
   export let currentDate: Date | null
+  export let timeZone: string = getUserTimezone()
   export let mondayStart: boolean = true
 
   const dispatch = createEventDispatcher()
@@ -25,6 +27,7 @@
 <div class="antiPopup popup">
   <Month
     bind:currentDate
+    {timeZone}
     {mondayStart}
     on:update={(result) => {
       if (result.detail !== undefined) {
diff --git a/packages/ui/src/components/calendar/TimeInputBox.svelte b/packages/ui/src/components/calendar/TimeInputBox.svelte
index ca01f98709..bd1ce745b4 100644
--- a/packages/ui/src/components/calendar/TimeInputBox.svelte
+++ b/packages/ui/src/components/calendar/TimeInputBox.svelte
@@ -16,11 +16,13 @@
   import { afterUpdate, createEventDispatcher } from 'svelte'
   import ui from '../../plugin'
   import Label from '../Label.svelte'
+  import moment from 'moment-timezone'
 
   export let currentDate: Date
   export let size: 'small' | 'medium' = 'medium'
   export let noBorder: boolean = false
   export let disabled: boolean = false
+  export let timeZone: string | undefined = undefined
 
   type TEdits = 'hour' | 'min'
   interface IEdits {
@@ -38,14 +40,16 @@
 
   const dispatch = createEventDispatcher()
 
-  const setValue = (val: number, date: Date | null, id: TEdits): Date => {
+  const setValue = (val: number, date: Date | null, id: TEdits, timeZone: string | undefined): Date => {
     if (date == null) date = new Date()
     switch (id) {
       case 'hour':
-        date.setHours(val)
+        date = new Date(timeZone ? moment(date).tz(timeZone).hours(val).valueOf() : moment(date).hours(val).valueOf())
         break
       case 'min':
-        date.setMinutes(val)
+        date = new Date(
+          timeZone ? moment(date).tz(timeZone).minutes(val).valueOf() : moment(date).minutes(val).valueOf()
+        )
         break
     }
     return date
@@ -61,23 +65,23 @@
     }
   }
 
-  const getValue = (date: Date, id: TEdits): number => {
+  const getValue = (date: Date, id: TEdits, timeZone: string | undefined): number => {
     switch (id) {
       case 'hour':
-        return date.getHours()
+        return timeZone ? moment(date).tz(timeZone).hours() : moment(date).hours()
       case 'min':
-        return date.getMinutes()
+        return timeZone ? moment(date).tz(timeZone).minutes() : moment(date).minutes()
     }
   }
 
-  const dateToEdits = (currentDate: Date | null): void => {
+  const dateToEdits = (currentDate: Date | null, timeZone: string | undefined): void => {
     if (currentDate == null) {
       edits.forEach((edit) => {
         edit.value = -1
       })
     } else {
       for (const edit of edits) {
-        edit.value = getValue(currentDate, edit.id)
+        edit.value = getValue(currentDate, edit.id, timeZone)
       }
     }
     edits = edits
@@ -85,7 +89,7 @@
 
   export const isNull = (currentDate?: Date): boolean => {
     if (currentDate !== undefined) {
-      dateToEdits(currentDate)
+      dateToEdits(currentDate, timeZone)
     }
     let result: boolean = false
     edits.forEach((edit, i) => {
@@ -113,8 +117,8 @@
         }
         if (!isNull() && !startTyping) {
           fixEdits()
-          currentDate = setValue(edits[index].value, currentDate, ed)
-          dateToEdits(currentDate)
+          currentDate = setValue(edits[index].value, currentDate, ed, timeZone)
+          dateToEdits(currentDate, timeZone)
         }
         edits = edits
         dispatch('update', currentDate)
@@ -132,8 +136,8 @@
         if (edits[index].value !== -1) {
           const val = ev.code === 'ArrowUp' ? edits[index].value + 1 : edits[index].value - 1
           if (currentDate) {
-            currentDate = setValue(val, currentDate, ed)
-            dateToEdits(currentDate)
+            currentDate = setValue(val, currentDate, ed, timeZone)
+            dateToEdits(currentDate, timeZone)
             dispatch('update', currentDate)
           }
         }
@@ -160,7 +164,7 @@
     dispatch('save')
   }
 
-  $: dateToEdits(currentDate)
+  $: dateToEdits(currentDate, timeZone)
   $: if (selected && edits[getIndex(selected)].el) edits[getIndex(selected)].el?.focus()
 
   afterUpdate(() => {
diff --git a/packages/ui/src/components/calendar/internal/DateUtils.ts b/packages/ui/src/components/calendar/internal/DateUtils.ts
index b16bfd0ad5..ce8de8d197 100644
--- a/packages/ui/src/components/calendar/internal/DateUtils.ts
+++ b/packages/ui/src/components/calendar/internal/DateUtils.ts
@@ -11,6 +11,8 @@
 // See the License for the specific language governing permissions and
 // limitations under the License.
 
+import { type TimeZone } from '../../../types'
+
 export const DAYS_IN_WEEK = 7
 
 export const MILLISECONDS_IN_MINUTE = 60000
@@ -127,6 +129,26 @@ export function getFormattedDate (value: number | null): string {
   return value === null ? '' : new Date(value).toLocaleString('default', { month: 'short', day: 'numeric' })
 }
 
-export const getTimeZoneName = (): string => {
-  return Intl.DateTimeFormat().resolvedOptions().timeZone?.split('/')[1] ?? ''
+export const getTimeZoneName = (val: string = Intl.DateTimeFormat().resolvedOptions().timeZone): string => {
+  return val.split('/')[1] ?? ''
+}
+
+export const convertTimeZone = (tz: string): TimeZone => {
+  const tzSpace = tz.replace(/_/gi, ' ')
+  const parts = tzSpace.split('/')
+  if (tz === '' || parts.length === 1) return { id: tz, continent: tzSpace, city: tzSpace, short: tzSpace }
+  return {
+    id: tz,
+    continent: parts[0],
+    city: parts.length > 2 ? `${parts[1]} - ${parts[2]}` : parts[1],
+    short: parts.length > 2 ? parts[2] : parts[1]
+  }
+}
+
+export function getUserTimezone (): string {
+  if (window.Intl !== undefined) {
+    return Intl.DateTimeFormat().resolvedOptions().timeZone
+  } else {
+    return 'Etc/GMT'
+  }
 }
diff --git a/packages/ui/src/components/internal/ClockPopup.svelte b/packages/ui/src/components/internal/ClockPopup.svelte
index 6be5bf5489..fa9b933cab 100644
--- a/packages/ui/src/components/internal/ClockPopup.svelte
+++ b/packages/ui/src/components/internal/ClockPopup.svelte
@@ -13,9 +13,9 @@
 // limitations under the License.
 -->
 <script lang="ts">
-  import { showPopup, TimeZone } from '../..'
+  import { convertTimeZone, showPopup, TimeZone } from '../..'
   import ClockFace from './ClockFace.svelte'
-  import TimeZonesPopup from './TimeZonesPopup.svelte'
+  import TimeZonesPopup from '../TimeZonesPopup.svelte'
 
   const clockSize: string = '80px'
   const tzs: string[] = []
@@ -30,17 +30,6 @@
   if (!Intl.supportedValuesOf) console.log('Your browser does not support Intl.supportedValuesOf().')
   else for (const timeZone of Intl.supportedValuesOf('timeZone')) tzs.push(timeZone)
 
-  const convertTimeZone = (tz: string): TimeZone => {
-    const tzSpace = tz.replaceAll('_', ' ')
-    const parts = tzSpace.split('/')
-    if (tz === '' || parts.length === 1) return { id: tz, continent: tzSpace, city: tzSpace, short: tzSpace }
-    return {
-      id: tz,
-      continent: parts[0],
-      city: parts.length > 2 ? `${parts[1]} - ${parts[2]}` : parts[1],
-      short: parts.length > 2 ? parts[2] : parts[1]
-    }
-  }
   if (tzs.length > 0) tzs.forEach((tz) => timeZones.push(convertTimeZone(tz)))
 
   const saveTZ = (): void => {
diff --git a/packages/ui/src/index.ts b/packages/ui/src/index.ts
index 976c5d9c08..4d1daff998 100644
--- a/packages/ui/src/index.ts
+++ b/packages/ui/src/index.ts
@@ -209,6 +209,7 @@ export { default as ModeSelector } from './components/ModeSelector.svelte'
 export { default as SimpleTimePopup } from './components/calendar/SimpleTimePopup.svelte'
 export { default as NumberInput } from './components/NumberInput.svelte'
 export { default as Lazy } from './components/Lazy.svelte'
+export { default as TimeZonesPopup } from './components/TimeZonesPopup.svelte'
 
 export * from './types'
 export * from './location'
diff --git a/plugins/calendar-resources/package.json b/plugins/calendar-resources/package.json
index c0b6b98f6b..a0c51c3372 100644
--- a/plugins/calendar-resources/package.json
+++ b/plugins/calendar-resources/package.json
@@ -51,6 +51,7 @@
     "@hcengineering/view-resources": "^0.6.0",
     "@hcengineering/view": "^0.6.9",
     "@hcengineering/workbench": "^0.6.9",
-    "fast-equals": "^2.0.3"
+    "fast-equals": "^2.0.3",
+    "moment-timezone": "^0.5.43"
   }
 }
diff --git a/plugins/calendar-resources/src/components/CreateEvent.svelte b/plugins/calendar-resources/src/components/CreateEvent.svelte
index 4fa5635c8f..9a7d6eaa29 100644
--- a/plugins/calendar-resources/src/components/CreateEvent.svelte
+++ b/plugins/calendar-resources/src/components/CreateEvent.svelte
@@ -18,19 +18,28 @@
   import { Class, Doc, Ref, getCurrentAccount } from '@hcengineering/core'
   import presentation, { createQuery, getClient } from '@hcengineering/presentation'
   import { StyledTextBox } from '@hcengineering/text-editor'
-  import { Button, EditBox, Icon, IconClose, IconMoreH, createFocusManager, showPopup } from '@hcengineering/ui'
+  import {
+    Button,
+    EditBox,
+    FocusHandler,
+    Icon,
+    IconClose,
+    IconMoreH,
+    createFocusManager,
+    getUserTimezone,
+    showPopup
+  } from '@hcengineering/ui'
   import { createEventDispatcher } from 'svelte'
   import calendar from '../plugin'
   import { saveUTC } from '../utils'
+  import CalendarSelector from './CalendarSelector.svelte'
   import EventParticipants from './EventParticipants.svelte'
   import EventReminders from './EventReminders.svelte'
   import EventTimeEditor from './EventTimeEditor.svelte'
   import EventTimeExtraButton from './EventTimeExtraButton.svelte'
+  import LocationEditor from './LocationEditor.svelte'
   import ReccurancePopup from './ReccurancePopup.svelte'
   import VisibilityEditor from './VisibilityEditor.svelte'
-  import CalendarSelector from './CalendarSelector.svelte'
-  import LocationEditor from './LocationEditor.svelte'
-  import FocusHandler from '@hcengineering/ui/src/components/FocusHandler.svelte'
 
   export let attachedTo: Ref<Doc> = calendar.ids.NoAttached
   export let attachedToClass: Ref<Class<Doc>> = calendar.class.Event
@@ -41,7 +50,6 @@
   const now = new Date()
   const defaultDuration = 60 * 60 * 1000
   const allDayDuration = 24 * 60 * 60 * 1000 - 1
-  // const offsetTZ = new Date().getTimezoneOffset() * 60 * 1000
 
   let startDate =
     date === undefined ? now.getTime() : withTime ? date.getTime() : date.setHours(now.getHours(), now.getMinutes())
@@ -49,6 +57,7 @@
   let dueDate = startDate + duration
   let allDay = false
   let location = ''
+  let timeZone: string = getUserTimezone()
 
   let reminders = [30 * 60 * 1000]
 
@@ -99,7 +108,8 @@
         location,
         allDay,
         access: 'owner',
-        originalStartTime: allDay ? saveUTC(date) : date
+        originalStartTime: allDay ? saveUTC(date) : date,
+        timeZone
       })
     } else {
       await client.addCollection(calendar.class.Event, space, attachedTo, attachedToClass, 'events', {
@@ -114,6 +124,7 @@
         title,
         location,
         allDay,
+        timeZone,
         access: 'owner'
       })
     }
@@ -168,8 +179,14 @@
     </div>
   </div>
   <div class="block first flex-no-shrink">
-    <EventTimeEditor {allDay} bind:startDate bind:dueDate focusIndex={10004} />
-    <EventTimeExtraButton bind:allDay bind:rules on:repeat={setRecurrance} on:allday={allDayChangeHandler} />
+    <EventTimeEditor {allDay} bind:startDate bind:dueDate {timeZone} focusIndex={10004} />
+    <EventTimeExtraButton
+      bind:allDay
+      bind:timeZone
+      bind:rules
+      on:repeat={setRecurrance}
+      on:allday={allDayChangeHandler}
+    />
   </div>
   <div class="block rightCropPadding">
     <LocationEditor focusIndex={10010} bind:value={location} />
diff --git a/plugins/calendar-resources/src/components/DateEditor.svelte b/plugins/calendar-resources/src/components/DateEditor.svelte
index c775871bef..54e763b9db 100644
--- a/plugins/calendar-resources/src/components/DateEditor.svelte
+++ b/plugins/calendar-resources/src/components/DateEditor.svelte
@@ -19,10 +19,11 @@
     ButtonSize,
     DatePopup,
     SimpleDatePopup,
-    eventToHTMLElement,
-    showPopup,
     TimeInputBox,
-    TimeShiftPresenter
+    TimeShiftPresenter,
+    eventToHTMLElement,
+    getUserTimezone,
+    showPopup
   } from '@hcengineering/ui'
   import { createEventDispatcher } from 'svelte'
   import DateLocalePresenter from './DateLocalePresenter.svelte'
@@ -36,6 +37,7 @@
   export let size: ButtonSize = 'medium'
   export let disabled: boolean = false
   export let focusIndex = -1
+  export let timeZone: string = getUserTimezone()
 
   const dispatch = createEventDispatcher()
 
@@ -45,7 +47,7 @@
     if (!showDate) {
       showPopup(
         DatePopup,
-        { currentDate, withTime: !withoutTime, label: ui.string.SelectDate, noShift: true },
+        { currentDate, withTime: !withoutTime, timeZone, label: ui.string.SelectDate, noShift: true },
         undefined,
         (res) => {
           if (res) {
@@ -58,7 +60,7 @@
   }
 
   function dateClick (e: MouseEvent) {
-    showPopup(SimpleDatePopup, { currentDate }, eventToHTMLElement(e), (res) => {
+    showPopup(SimpleDatePopup, { currentDate, timeZone }, eventToHTMLElement(e), (res) => {
       if (res) {
         date = res.getTime()
         dispatch('update', date)
@@ -80,10 +82,11 @@
   {#if showDate || withoutTime}
     <Button {kind} {size} padding={'0 .5rem'} {focusIndex} on:click={dateClick} {disabled}>
       <svelte:fragment slot="content">
-        <DateLocalePresenter date={currentDate.getTime()} />
+        <DateLocalePresenter date={currentDate.getTime()} {timeZone} />
       </svelte:fragment>
     </Button>
   {/if}
+
   {#if !withoutTime}
     <Button
       {kind}
@@ -96,6 +99,7 @@
       <svelte:fragment slot="content">
         <TimeInputBox
           bind:currentDate
+          {timeZone}
           noBorder
           size={'small'}
           on:update={(date) => {
diff --git a/plugins/calendar-resources/src/components/DateLocalePresenter.svelte b/plugins/calendar-resources/src/components/DateLocalePresenter.svelte
index 431a6d89bb..3e16654c4a 100644
--- a/plugins/calendar-resources/src/components/DateLocalePresenter.svelte
+++ b/plugins/calendar-resources/src/components/DateLocalePresenter.svelte
@@ -13,9 +13,14 @@
 // limitations under the License.
 -->
 <script lang="ts">
+  import { getUserTimezone } from '@hcengineering/ui'
+
   export let date: number
+  export let timeZone: string = getUserTimezone()
+
   const current = new Date()
   let options: Intl.DateTimeFormatOptions = {
+    timeZone,
     day: 'numeric',
     weekday: 'short',
     month: 'short'
@@ -26,6 +31,8 @@
       year: '2-digit'
     }
   }
+
+  $: options.timeZone = timeZone
 </script>
 
 {new Date(date).toLocaleDateString('default', options)}
diff --git a/plugins/calendar-resources/src/components/EditEvent.svelte b/plugins/calendar-resources/src/components/EditEvent.svelte
index cb85cb6d74..7fbb4fc64f 100644
--- a/plugins/calendar-resources/src/components/EditEvent.svelte
+++ b/plugins/calendar-resources/src/components/EditEvent.svelte
@@ -18,20 +18,28 @@
   import { DocumentUpdate, Ref } from '@hcengineering/core'
   import presentation, { getClient } from '@hcengineering/presentation'
   import { StyledTextBox } from '@hcengineering/text-editor'
-  import { Button, EditBox, Icon, IconClose, createFocusManager, showPopup } from '@hcengineering/ui'
+  import {
+    Button,
+    EditBox,
+    FocusHandler,
+    Icon,
+    IconClose,
+    createFocusManager,
+    getUserTimezone,
+    showPopup
+  } from '@hcengineering/ui'
   import { deepEqual } from 'fast-equals'
   import { createEventDispatcher } from 'svelte'
   import calendar from '../plugin'
   import { isReadOnly, saveUTC, updateReccuringInstance } from '../utils'
+  import CalendarSelector from './CalendarSelector.svelte'
   import EventParticipants from './EventParticipants.svelte'
   import EventReminders from './EventReminders.svelte'
   import EventTimeEditor from './EventTimeEditor.svelte'
   import EventTimeExtraButton from './EventTimeExtraButton.svelte'
+  import LocationEditor from './LocationEditor.svelte'
   import ReccurancePopup from './ReccurancePopup.svelte'
   import VisibilityEditor from './VisibilityEditor.svelte'
-  import CalendarSelector from './CalendarSelector.svelte'
-  import LocationEditor from './LocationEditor.svelte'
-  import FocusHandler from '@hcengineering/ui/src/components/FocusHandler.svelte'
 
   export let object: Event
   $: readOnly = isReadOnly(object)
@@ -48,6 +56,7 @@
   let visibility = object.visibility ?? 'public'
   let reminders = [...(object.reminders ?? [])]
   let space = object.space
+  let timeZone: string = object.timeZone ?? getUserTimezone()
 
   let description = object.description
   let location = object.location
@@ -84,6 +93,9 @@
     if (object.location !== location) {
       update.location = location
     }
+    if (object.timeZone !== timeZone) {
+      update.timeZone = timeZone
+    }
     if (allDay !== object.allDay) {
       update.date = allDay ? saveUTC(startDate) : startDate
       update.dueDate = allDay ? saveUTC(dueDate) : dueDate
@@ -170,8 +182,16 @@
     </div>
   </div>
   <div class="block first flex-no-shrink">
-    <EventTimeEditor {allDay} bind:startDate bind:dueDate disabled={readOnly} focusIndex={10004} />
-    <EventTimeExtraButton bind:allDay bind:rules on:repeat={setRecurrance} on:allday={allDayChangeHandler} noRepeat />
+    <EventTimeEditor {allDay} bind:startDate {timeZone} bind:dueDate disabled={readOnly} focusIndex={10004} />
+    <EventTimeExtraButton
+      bind:allDay
+      bind:timeZone
+      bind:rules
+      on:repeat={setRecurrance}
+      {readOnly}
+      on:allday={allDayChangeHandler}
+      noRepeat
+    />
   </div>
   <div class="block rightCropPadding">
     <LocationEditor bind:value={location} focusIndex={10005} />
diff --git a/plugins/calendar-resources/src/components/EventTimeEditor.svelte b/plugins/calendar-resources/src/components/EventTimeEditor.svelte
index 9634c714af..45b6bc51a3 100644
--- a/plugins/calendar-resources/src/components/EventTimeEditor.svelte
+++ b/plugins/calendar-resources/src/components/EventTimeEditor.svelte
@@ -13,18 +13,20 @@
 // limitations under the License.
 -->
 <script lang="ts">
-  import { Icon, areDatesEqual, IconArrowRight } from '@hcengineering/ui'
+  import { Icon, IconArrowRight, getUserTimezone } from '@hcengineering/ui'
+  import moment from 'moment-timezone'
+  import { createEventDispatcher } from 'svelte'
   import calendar from '../plugin'
   import DateEditor from './DateEditor.svelte'
-  import { createEventDispatcher } from 'svelte'
 
   export let startDate: number
   export let dueDate: number
   export let allDay: boolean
   export let disabled: boolean = false
+  export let timeZone: string = getUserTimezone()
   export let focusIndex = -1
 
-  $: sameDate = areDatesEqual(new Date(startDate), new Date(dueDate))
+  $: sameDate = moment(startDate).tz(timeZone).isSame(moment(dueDate).tz(timeZone), 'date')
 
   let diff = dueDate - startDate
   const allDayDuration = 24 * 60 * 60 * 1000 - 1
@@ -56,6 +58,7 @@
     bind:date={startDate}
     direction={sameDate ? 'horizontal' : 'vertical'}
     withoutTime={allDay}
+    {timeZone}
     on:update={dateChange}
     {disabled}
     {focusIndex}
@@ -70,6 +73,7 @@
     showDate={!sameDate}
     difference={startDate}
     {disabled}
+    {timeZone}
     focusIndex={focusIndex !== -1 ? focusIndex + 1 : focusIndex}
     on:update={dueChange}
   />
diff --git a/plugins/calendar-resources/src/components/EventTimeExtraButton.svelte b/plugins/calendar-resources/src/components/EventTimeExtraButton.svelte
index f304830ec8..88aa645954 100644
--- a/plugins/calendar-resources/src/components/EventTimeExtraButton.svelte
+++ b/plugins/calendar-resources/src/components/EventTimeExtraButton.svelte
@@ -14,28 +14,67 @@
 -->
 <script lang="ts">
   import { RecurringRule } from '@hcengineering/calendar'
-  import { Button, CheckBox, Icon, Label, MILLISECONDS_IN_MINUTE } from '@hcengineering/ui'
+  import {
+    Button,
+    CheckBox,
+    Icon,
+    Label,
+    TimeZone,
+    TimeZonesPopup,
+    convertTimeZone,
+    eventToHTMLElement,
+    getUserTimezone,
+    showPopup
+  } from '@hcengineering/ui'
   import { createEventDispatcher } from 'svelte'
   import calendar from '../plugin'
   import RRulePresenter from './RRulePresenter.svelte'
+  import TimeZoneSelector from './TimeZoneSelector.svelte'
 
   export let allDay: boolean
   export let rules: RecurringRule[] = []
   export let noRepeat: boolean = false
+  export let timeZone: string
+  export let readOnly: boolean = false
+
+  const myTimezone = getUserTimezone()
 
   const dispatch = createEventDispatcher()
 
-  const offsetTZ = new Date().getTimezoneOffset() * 60 * 1000
+  function showTimezoneSelector (e: MouseEvent) {
+    const timeZones: TimeZone[] = []
+    const tzs: string[] = []
+    if (!Intl.supportedValuesOf) console.log('Your browser does not support Intl.supportedValuesOf().')
+    else for (const timeZone of Intl.supportedValuesOf('timeZone')) tzs.push(timeZone)
+
+    if (tzs.length > 0) tzs.forEach((tz) => timeZones.push(convertTimeZone(tz)))
+    showPopup(
+      TimeZonesPopup,
+      {
+        timeZones,
+        withAdd: false,
+        selected: timeZone,
+        count: 1,
+        reset: null
+      },
+      eventToHTMLElement(e),
+      (result) => {
+        if (result !== undefined) {
+          timeZone = result
+        }
+      }
+    )
+  }
 </script>
 
-{#if !allDay && rules.length === 0}
+{#if !allDay && rules.length === 0 && myTimezone === timeZone}
   <div class="antiButton ghost x-small sh-no-shape text-11px pl-2 pr-2 pt-1 pb-1 mt-1 ml-5-5 gap-3 w-min">
     <!-- svelte-ignore a11y-click-events-have-key-events -->
     <!-- svelte-ignore a11y-no-static-element-interactions -->
     <div class="overflow-label cursor-pointer" on:click={() => (allDay = true)}>
       <Label label={calendar.string.AllDay} />
     </div>
-    <div class="overflow-label cursor-default">
+    <div class="overflow-label cursor-default" on:click={showTimezoneSelector}>
       <Label label={calendar.string.TimeZone} />
     </div>
     {#if !noRepeat}
@@ -54,6 +93,7 @@
       kind={'ghost'}
       padding={'0 .5rem'}
       justify={'left'}
+      disabled={readOnly}
       on:click={() => {
         allDay = !allDay
         dispatch('allday')
@@ -62,13 +102,7 @@
   </div>
   <div class="flex-row-center gap-1-5 mt-1">
     <Icon icon={calendar.icon.Globe} size={'small'} fill={'var(--theme-dark-color)'} />
-    <Button label={calendar.string.TimeZone} kind={'ghost'} padding={'0 .5rem'} justify={'left'}>
-      <svelte:fragment slot="content">
-        <span class="ml-2 content-darker-color">
-          GMT{(offsetTZ > 0 ? '-' : '+') + Math.abs(offsetTZ / MILLISECONDS_IN_MINUTE / 60)}
-        </span>
-      </svelte:fragment>
-    </Button>
+    <TimeZoneSelector bind:timeZone disabled={readOnly} />
   </div>
   {#if !noRepeat}
     <div class="flex-row-center gap-1-5 mt-1">
@@ -78,6 +112,7 @@
         kind={'ghost'}
         padding={'0 .5rem'}
         justify={'left'}
+        disabled={readOnly}
         on:click={() => dispatch('repeat')}
       >
         <svelte:fragment slot="content">
diff --git a/plugins/calendar-resources/src/components/TimeZoneSelector.svelte b/plugins/calendar-resources/src/components/TimeZoneSelector.svelte
new file mode 100644
index 0000000000..b34a202367
--- /dev/null
+++ b/plugins/calendar-resources/src/components/TimeZoneSelector.svelte
@@ -0,0 +1,62 @@
+<!--
+// Copyright © 2023 Hardcore Engineering Inc.
+//
+// Licensed under the Eclipse Public License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License. You may
+// obtain a copy of the License at https://www.eclipse.org/legal/epl-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+//
+// See the License for the specific language governing permissions and
+// limitations under the License.
+-->
+<script lang="ts">
+  import {
+    Button,
+    TimeZone,
+    TimeZonesPopup,
+    convertTimeZone,
+    eventToHTMLElement,
+    getTimeZoneName,
+    showPopup
+  } from '@hcengineering/ui'
+  import calendar from '../plugin'
+
+  export let timeZone: string
+  export let disabled: boolean = false
+
+  function open (e: MouseEvent) {
+    const timeZones: TimeZone[] = []
+    const tzs: string[] = []
+    if (!Intl.supportedValuesOf) console.log('Your browser does not support Intl.supportedValuesOf().')
+    else for (const timeZone of Intl.supportedValuesOf('timeZone')) tzs.push(timeZone)
+
+    if (tzs.length > 0) tzs.forEach((tz) => timeZones.push(convertTimeZone(tz)))
+    showPopup(
+      TimeZonesPopup,
+      {
+        timeZones,
+        withAdd: false,
+        selected: timeZone,
+        count: 1,
+        reset: null
+      },
+      eventToHTMLElement(e),
+      (result) => {
+        if (result !== undefined) {
+          timeZone = result
+        }
+      }
+    )
+  }
+</script>
+
+<Button {disabled} label={calendar.string.TimeZone} kind={'ghost'} padding={'0 .5rem'} justify={'left'} on:click={open}>
+  <svelte:fragment slot="content">
+    <span class="ml-2 content-darker-color">
+      {getTimeZoneName(timeZone)}
+    </span>
+  </svelte:fragment>
+</Button>
diff --git a/plugins/calendar-resources/src/index.ts b/plugins/calendar-resources/src/index.ts
index 5c57d3bb83..d35bd19e25 100644
--- a/plugins/calendar-resources/src/index.ts
+++ b/plugins/calendar-resources/src/index.ts
@@ -102,7 +102,8 @@ async function deleteRecHandler (res: any, object: ReccuringInstance): Promise<v
         rules: object.rules,
         exdate: object.exdate,
         visibility: object.visibility,
-        access: object.access
+        access: object.access,
+        timeZone: object.timeZone
       },
       object._id
     )
diff --git a/plugins/calendar-resources/src/utils.ts b/plugins/calendar-resources/src/utils.ts
index 0b1c4e8522..2b9960405b 100644
--- a/plugins/calendar-resources/src/utils.ts
+++ b/plugins/calendar-resources/src/utils.ts
@@ -162,6 +162,7 @@ export async function updateReccuringInstance (
                   rules: object.rules,
                   exdate: object.exdate,
                   rdate: object.rdate,
+                  timeZone: object.timeZone,
                   ...ops
                 },
                 object._id
diff --git a/plugins/calendar/src/index.ts b/plugins/calendar/src/index.ts
index d5ea44f162..de6611acfb 100644
--- a/plugins/calendar/src/index.ts
+++ b/plugins/calendar/src/index.ts
@@ -69,6 +69,7 @@ export interface ReccuringEvent extends Event {
   exdate: Timestamp[]
   rdate: Timestamp[]
   originalStartTime: Timestamp
+  timeZone: string
 }
 
 /**
@@ -101,6 +102,8 @@ export interface Event extends AttachedDoc {
   visibility?: Visibility
 
   access: 'freeBusyReader' | 'reader' | 'writer' | 'owner'
+
+  timeZone?: string
 }
 
 /**