How to fix Outlook calendar reminders not firing or showing at the wrong time on Windows and Mac

Summary

This guide helps you troubleshoot and resolve: How to fix Outlook calendar reminders not firing or showing at the wrong time on Windows and Mac. Follow the steps below to fix the issue.

Common Causes

Outlook calendar reminders are essential for staying on top of meetings, appointments, and deadlines. When they stop firing, play silently, or pop up at the wrong time, it usually comes down to a handful of common causes: incorrect time zone settings, a corrupted Outlook profile, conflicting calendar sources, or sound and notification configurations that have been switched off. The good news is that most of these issues can be resolved without contacting support. This guide walks you through the fixes that resolve the vast majority of Outlook calendar reminder problems on both Windows and macOS.

Quick Fix Steps

If you are short on time, work through these steps in order. Most reminder issues are resolved by the time you reach the end of the list.

1. Confirm your computer's time zone and time are correct.
2. Open Outlook and verify the time zone set in File > Options > Calendar (Windows) or Outlook > Settings > Calendar (Mac).
3. Check that reminders are actually enabled for the affected appointment.
4. Make sure Outlook is set to play a reminder sound and that your system volume is not muted.
5. Confirm Windows Focus Assist (quiet hours) or macOS Do Not Disturb is not suppressing notifications.
6. Restart Outlook completely and test with a new appointment set a few minutes in the future.
7. If the issue persists, repair your Outlook data file or rebuild your Outlook profile.

Detailed Instructions

Verify System Time and Time Zone

Reminders rely on your computer clock. If the clock is wrong, reminders will fire at the wrong time or not at all.

1. On Windows, right-click the clock in the taskbar and choose Adjust date and time. Toggle Set time automatically on.
2. On macOS, open System Settings > General > Date & Time and enable Set time and date automatically using Apple's time server.
3. Confirm the time zone matches your actual location, particularly if you have travelled recently or work across states.

Check Outlook's Time Zone Setting

Outlook has its own time zone setting that can drift out of sync with your system clock.

1. Windows: Click File > Options > Calendar. Under Time zones, confirm the correct zone is selected and that the Adjust for daylight saving time box is ticked if applicable.
2. Mac (new Outlook): Click Outlook > Settings > Calendar. Under Time zones, verify the zone and daylight saving option.
3. Mac (legacy Outlook): Click Outlook > Preferences > Calendar and adjust the time zone under Time zones.

Confirm Reminders Are Enabled for the Appointment

Individual appointments can have their reminders turned off, which overrides the default reminder setting.

1. Open the affected appointment and double-click to edit it.
2. In the Reminder dropdown (on the Appointment tab in Windows, or the Reminder field on Mac), confirm it is set to a value other than None.
3. Click Save & Close or press Command + S on Mac.

Set the Default Reminder Behaviour

If reminders are missing across many appointments, the default may have been turned off.

1. Windows: Go to File > Options > Calendar. Under Calendar options, set Default reminders to a value such as 15 minutes or 30 minutes.
2. Mac (new Outlook): Go to Outlook > Settings > Calendar. Under Reminders, adjust the default for each calendar type (Appointments, Meetings, All-day events).
3. Mac (legacy Outlook): Go to Outlook > Preferences > Reminders and Notifications and adjust the defaults there.

Restore the Reminder Sound

Reminders may appear silently if the sound file is missing or muted.

1. Windows: Open Control Panel > Sound. In the Sounds tab, under Program Events, locate Microsoft Outlook and set Reminder to a sound such as Reminder.wav.
2. Mac: Open System Settings > Notifications > Outlook. Enable Play sound for notifications and ensure Outlook is allowed to send notifications.
3. Check that your computer is not muted and the volume is turned up.

Check Focus Assist and Do Not Disturb

Operating system quiet modes can suppress reminder popups even when Outlook is configured correctly.

1. Windows: Click the notification icon on the taskbar and turn off Focus Assist (or set it to Alarms only). You can also go to Settings > System > Focus to configure it.
2. Mac: Open System Settings > Focus and turn off any active Focus mode, or allow Outlook notifications within the Focus settings.

Allow Outlook to Run in the Background

Reminders only fire while Outlook is running. If Outlook is closed or suspended, reminders will not appear.

1. Windows: Click File > Options > Advanced. Under Outlook start and exit, tick Minimise to the system tray instead of closing if available, and ensure Hide When Minimized is checked so Outlook continues running in the background.
2. Mac: Quit Outlook using Command + Q rather than just closing the window, then reopen it. Check System Settings > General > Login Items to confirm Outlook is allowed to run in the background.

Disable Add-ins That Interfere with Reminders

Third-party add-ins, particularly calendar sync tools, can suppress or delay reminders.

1. Windows: Click File > Options > Add-ins. At the bottom, choose COM Add-ins and click Go. Untick any non-essential add-ins and click OK. Restart Outlook.
2. Mac: Click Tools > Manage Add-ins (or the add-ins icon on the ribbon). Disable any add-ins you do not recognise or no longer need, then restart Outlook.
3. For a thorough check, restart Outlook in Safe Mode (hold Ctrl while clicking the Outlook shortcut on Windows) to load without add-ins and confirm whether the issue persists.

Check for Conflicting Calendars

If you have multiple calendars connected (such as Google, iCloud, or shared mailboxes), reminders may fire for the wrong calendar or be suppressed entirely.

1. Open Calendar in Outlook and look at the left-hand panel. Note any calendars that may be duplicated or out of sync.
2. Right-click a connected calendar and choose Properties (Windows) or Calendar Permissions (Mac) to confirm it is enabled and that reminders are not disabled at the calendar level.
3. If you use Google Calendar via Google Calendar Sync or OAuth, confirm the connection is still authorised. Re-authenticate if prompted.

Troubleshooting

Repair the Outlook Data File (Windows)

A corrupted mailbox can prevent reminders from being read correctly.

1. Close Outlook.
2. Open Control Panel > Mail > Show Profiles > Properties > Data Files.
3. Select your OST or PST file, click Open File Location, then close Outlook.
4. Run ScanPST.exe (the Inbox Repair Tool) from your Office installation folder, typically C:\Program Files\Microsoft Office\root\Office16\.
5. Browse to the data file, click Start, and follow the prompts to repair any errors.
6. Restart Outlook and test a reminder.

Rebuild the Outlook Profile

If repairing the data file does not resolve the issue, the Outlook profile itself may be corrupted.

1. Windows: Open Control Panel > Mail > Show Profiles. Click Add, give the new profile a name, and configure your email account. Set the new profile as the default and restart Outlook.
2. Mac: Quit Outlook. Open System Settings > Internet Accounts, remove the affected account, then re-add it. Restart Outlook.
3. Test a reminder with a new appointment to confirm the issue is resolved.

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