How to Set Up Microsoft 365 Number Matching in the Authenticator App to Prevent MFA Fatigue Attacks

Security & Access KB-1025

Summary

This guide helps you troubleshoot and resolve: How to Set Up Microsoft 365 Number Matching in the Authenticator App to Prevent MFA Fatigue Attacks. Follow the steps below to fix the issue.

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Common Causes

Microsoft 365 number matching adds a critical layer of security to your multi-factor authentication (MFA). Instead of simply tapping Approve on a notification, you must enter a two-digit number shown on your computer screen into the Microsoft Authenticator app on your mobile device. This prevents MFA fatigue attacks, where attackers spam approval requests in the hope that a user will accidentally accept one out of frustration or habit.

Number matching is enabled by your organisation’s IT administrator. Once it is turned on for your account, you will see it automatically during sign-in—there is no setting to switch on within the app itself.

Before you begin

You have a Microsoft 365 work or school account.
The Microsoft Authenticator app is installed on your iOS or Android device.
Your work or school account is already added to the Microsoft Authenticator app.
Your organisation’s IT administrator has enabled number matching for your tenant.

Using number matching during sign-in

Enter your Microsoft 365 email address and password on the sign-in page.
A two-digit number appears on your computer screen.
Open the Microsoft Authenticator app on your mobile device.
Enter the exact two-digit number shown on your screen.
Tap Yes to complete the sign-in.

Troubleshooting

Number matching prompt is not appearing

Confirm with your IT administrator that number matching has been enabled for your account or organisation.
Ensure you are using the Microsoft Authenticator app, not a third-party authenticator app.
Check that your mobile device has an active internet connection.

App is not receiving notifications

Verify that notifications are enabled for the Microsoft Authenticator app in your phone settings.
Ensure your device is not in Do Not Disturb or Focus mode.
Try signing out and back into your account within the app.

Number matching is designed to stop accidental approvals. If you receive a number matching request that you did not initiate, do not enter the number. Change your password immediately and contact your IT support.

Never share the two-digit number shown on your screen with anyone. Microsoft or your IT support team will never ask you to provide an MFA code over the phone or by email.

If you are unable to complete sign-in or experience ongoing issues with Microsoft 365 MFA, Open a Ticket with our Brisbane support team.

For help resetting your Windows login password, see our guide on Password reset (Windows login).

Still Having Issues?

Need more help? If the issue persists after trying these steps, please open a support ticket and our team will assist you.

💻 Open a Ticket