My work iphone calendar will not sync with outlook calendar

First identify whether the missing events exist in Outlook on the web and which iPhone app is affected, then reset the corresponding mobile synchronization connection.

1. Locate where synchronization stops

1. Open the work calendar in Outlook on the web.
2. Search for several events that are missing on the iPhone.
   • Present online but missing on iPhone: the mailbox data is intact; continue with the appropriate app branch below.
   • Missing online too: those events may have been saved to a different calendar, such as iCloud or “On My iPhone,” rather than the work mailbox.
3. On the iPhone, open one affected event and inspect its Calendar field. Confirm it belongs to the work account.
4. Determine whether the issue occurs in:
   • Outlook for iOS, or
   • Apple’s built-in Calendar app.

2. If events are missing in Outlook for iOS

1. Open Outlook → Calendar.
2. Tap the calendar icon or profile picture in the upper-left corner.
3. Confirm that the relevant work calendar is listed and checkmarked.
4. Go to Outlook → Settings → Accounts → affected work account.
5. Check the account type shown at the top:
   • If it is IMAP or POP, that configuration cannot synchronize calendars; the account must be configured as Microsoft 365/Exchange.
   • Otherwise, tap Reset Account, reopen Outlook, and allow it to resynchronize. ^1^

If resetting does not help:

1. Return to Outlook → Settings → affected account.
2. Select Delete Account → Delete From This Device.
3. Add the work account again using its Microsoft 365/Exchange sign-in.

Deleting it from the device removes the local connection, not the calendar stored in the work mailbox. Microsoft also recommends restarting and updating Outlook before using the more disruptive offload/reinstallation option. ^2^

3. If events are missing in Apple Calendar

1. Open iPhone Settings → Apps → Mail → Mail Accounts → work account.
2. Confirm Calendars is enabled.
3. Open Calendar, tap Calendars, and confirm the work calendar is selected.
4. If there is no Calendars switch, the account may have been configured as IMAP. Remove it and add it as Exchange, not IMAP or POP. ^1^

If only some events remain missing and they are present in Outlook on the web, rebuild the Exchange ActiveSync relationship:

1. Remove the work account from the iPhone.
2. In Outlook on the web, open Settings → Options → Phone → Mobile Phones/Mobile Devices.
3. Select the old iPhone relationship and delete it.
4. Restart the iPhone.
5. Add the work account again as Exchange, then verify the missing events appear.

Microsoft documents this procedure specifically for Exchange Online calendars where some mobile and mailbox events are out of sync. ^3^

4. If this is a managed work iPhone

Contact the Microsoft 365 or Intune administrator if:

• Sync Calendars is absent or disabled in Outlook.
• The account cannot be removed or reset.
• Re-adding it requires company enrollment.
• Outlook works, but synchronization into Apple Calendar does not.

An organization can use Intune App Protection and App Configuration policies to block synchronization of work-calendar data into native apps, even while allowing other Outlook features. ^4^

References

1. Outlook app
2. Troubleshoot Outlook mobile issues | Microsoft Support
3. Calendar on mobile device isn't synced to the calendar in an Exchange Online mailbox when you use Exchange ActiveSync
4. Deploying Outlook for iOS and Android app configuration settings in Exchange Online