Microsoft 365 Keeps Asking You to Sign In on a Mac: What to Check
Word, Excel or Outlook keeps asking you to sign in on a Mac? Check the licensed account, app location and saved credentials before reinstalling Office.
This guide is for Word, Excel, PowerPoint or Outlook repeatedly asking for a Microsoft 365 sign-in, reporting no licence or returning to an activation screen. It is not for an app that crashes or will not open at all. For that, see Microsoft 365 apps not opening on a Mac.
A sign-in loop usually comes down to the wrong account, a licence that is missing or expired, Office apps moved from Applications, or saved credentials that no longer match the account.
Confirm which account owns the licence
Many people have a personal Microsoft account and a work account with similar email addresses. Only the account that owns or has been assigned the licence can activate the desktop apps.
For a personal subscription, sign in to the Microsoft account used to buy Microsoft 365 and check that the subscription is current. For a business account, ask the Microsoft 365 administrator to confirm the desktop-app licence is assigned to the user.
Access to the free web apps does not prove that the account has a desktop-app licence.
Sign out of the wrong account
Open one Office app, such as Word, and review the signed-in account. Sign out of accounts that should not be activating Office, quit every Office app and open Word again.
Choose Sign In and use the licensed account. If the Mac belongs to a business, do not substitute a personal Microsoft account just to clear the message. That can mix personal storage and work documents.
Make sure the apps are in Applications
Microsoft notes that repeated sign-in or Keychain prompts can occur when an Office app has been moved from the normal Applications folder.
Open Finder, Applications and check that Word, Excel, PowerPoint and Outlook are there. Do not run them from a downloaded disk image, an old backup folder or the Bin.
Update Office and macOS
Install current Office updates and restart the Mac. A restart is especially useful after a password change, licence assignment or Office update.
If one app signs in correctly but another does not, compare their versions before changing account credentials.
Treat repeated Keychain prompts carefully
A Keychain prompt is macOS asking whether an app can use saved credentials. Enter the Mac login password when the prompt is legitimate and belongs to a Microsoft app you just opened.
If the same prompt returns every time, do not delete every Microsoft or Office entry from Keychain. The safer approach is to confirm the account and licence first, then reset only the Office activation credentials using Microsoft’s current activation troubleshooter or licence-removal process.
Clearing broad Keychain items can sign other services out or remove saved information you still need.
Reinstall only after the licence is confirmed
Reinstalling Office will not create a licence or fix an account that has no desktop-app entitlement. It can help when the app installation or activation components are damaged, but it should come after the account, licence, app location and updates have been checked.
If Office was activated with the wrong licence, remove the Office licence files and reactivate with the correct account rather than repeatedly signing in over the top.
Keep work and personal accounts clear
For a business Mac, use the work account for Office activation, OneDrive and business email. Keep personal Microsoft accounts out of work OneDrive folders unless there is a deliberate reason to use them.
Our guide to keeping personal and business accounts separate explains the wider approach.
Need a hand?
For help with Microsoft 365 licensing, sign-in loops or account clean-up on a Mac, see Microsoft 365 & Email or contact Your Mac Tech.
