Where to change your Office 365 username
Your Office 365 username lives in your account settings, not in the individual apps like Word or Excel. You reach it through the Microsoft account portal, which controls the sign-in name you use across all Microsoft services. The change takes effect within a few minutes, though some apps may need you to sign out and back in before they recognize the new name.
The process differs slightly depending on whether you manage your own account or your workplace does. If your company runs Office 365 through a business subscription, your IT department may have locked down username changes — you would need to contact them directly. If you have a personal Microsoft account or a home subscription, you can make the change yourself in about five minutes.
Key Takeaways
- Personal Microsoft accounts let you change your username through the account settings portal; work accounts usually require your IT department to make the change.
- You can add a new email address as your sign-in name without deleting the old one, so your contacts can still reach you at the original address.
- The username change takes effect when ready in the portal but may take a few minutes to sync across Outlook, OneDrive, and other Microsoft apps.
- If you forget your new username, you can always sign in using any email address linked to your account, then check your settings to confirm which one is primary.
Steps to change your username on a personal account
Start by going to account.microsoft.com in your web browser and signing in with your current username and password. Once you are logged in, look for the "Your info" option in the left sidebar — this is where Microsoft stores your account details.
Click "Manage your Microsoft account" or "View your account" (the exact wording varies by region). You will see a section labeled "Email and phone" or "Sign-in options." This is where your current username appears. Next to it, you should see an option to "Add email" or "Add sign-in method." Click that button to add a new email address that you want to use as your username instead.
Type in the new email address you want to use. Microsoft will send a verification code to that address — check your inbox (or spam folder) and enter the code back into the portal. Once verified, you can set this new address as your primary sign-in name. Look for a button or checkbox that says "Make primary" or "Set as sign-in name" and click it.
Your old username does not disappear. It remains linked to your account as a recovery option, so anyone who knows your original email can still reach you, and you can still use it to sign in if you forget the new one. The change is complete once you see the new address listed as your primary sign-in method.
What happens if your account is managed by your workplace
If you signed up for Office 365 through your employer or school, your username is usually controlled by your organization's IT department or administrator. These accounts are called work or school accounts, and they follow your organization's policies rather than Microsoft's standard account settings.
In this case, you cannot change your username yourself through the Microsoft portal. Instead, contact your IT help desk or HR department and ask them to change your sign-in name. They have the tools to do this on their end, and they can may support the change does not break your access to shared files, email, or other work resources.
The wait time depends on your organization's process — some make the change within an hour, while others may take a day or two. Ask your IT department for a timeline so you know when to expect the change to take effect.
Signing in after you change your username
Once your new username is set as primary, use it the next time you sign into Office 365, Outlook, OneDrive, or any other Microsoft app. You do not need to update anything in the apps themselves — they pull your sign-in name from your Microsoft account automatically.
If an app keeps asking you to sign in again after the change, sign out completely, close the app, and then sign back in with your new username. This forces the app to refresh its connection to your account. On mobile devices, you may need to remove the account from the app's settings and add it again with the new username.
Your old username still works as a backup sign-in method. If you ever forget your new username or need to sign in on a device where you are not sure which name to use, enter your old email address — Microsoft will recognize it and let you in.
Syncing the change across Office apps on your computer
If you use Office desktop applications like Word, Excel, or PowerPoint on Windows or Mac, the username change may take a few minutes to sync. You do not need to do anything — Microsoft handles this in the background. However, if an app shows your old username in the top right corner or asks you to sign in again, you can speed up the process.
On Windows, open File Explorer, navigate to C:\Users\[your username]\AppData\Local\Microsoft\Office, and look for a file called "16.0_user.dat" or similar. Deleting this file forces Office to refresh your account information the next time you open an app. On Mac, open Finder, press Command+Shift+G, type ~/Library/Containers/com.microsoft.Word/Data/Library/Preferences, and delete the com.microsoft.Word.plist file.
After you delete the file, close all Office apps completely and reopen one of them. You may be asked to sign in again — use your new username. Once you sign in, the change will sync across all your Office apps within a few minutes.
Troubleshooting: What to do if the change does not work
If you added a new email address but cannot set it as your primary sign-in name, the address may not have been fully verified. Go back to account.microsoft.com, find the email address in your sign-in options, and look for a "Verify" button. Click it and check your email for a verification code, then enter it back into the portal. Only verified addresses can be set as primary.
If you are still unable to change your username after verification, try signing out of your Microsoft account completely, closing your browser, and signing back in. Sometimes the portal needs a fresh session to show all available options. If the problem persists and you have a work account, contact your IT department — they may have restrictions in place that prevent self-service changes.
If you changed your username but Office apps still show the old one after several hours, try signing out of your Microsoft account in Windows or Mac system settings, waiting five minutes, and signing back in. This clears the cached account information and forces a full sync with Microsoft's servers.
Frequently Asked Questions
Can I change my username back to the old one if I change my mind?
Yes. Go back to account.microsoft.com, find your sign-in options, and set your original email address as primary again. The old address is always linked to your account, so you can switch between them as many times as you need.
Will changing my username affect my OneDrive or SharePoint files?
No. Your files stay in your OneDrive and SharePoint accounts regardless of what username you use to sign in. The username is just the key that opens the door — it does not change what is behind it.
What if I do not have a second email address to use as my new username?
You can create a new email address through Outlook.com for free and link it to your Microsoft account, then set it as your primary sign-in name. Alternatively, if you have a Gmail or other email address, you can add that to your Microsoft account and use it as your username.
How long does it take for the username change to show up everywhere?
The change is when ready in your Microsoft account settings, but it may take a few minutes to sync to Outlook, OneDrive, Teams, and other apps. If an app does not recognize the change within 15 minutes, sign out and back in to force a refresh.
Do I need to update my password when I change my username?
No. Your password stays the same — only your sign-in name changes. You will use the same password with your new username.