Install and activate Office: new keys, reinstalls and errors

For an eligible retail Office key, associate it with your Microsoft account and install the product from that same account. If you already redeemed the key yourself, reinstall through the associated account rather than treating it as a new code. Organisational, LTSC and special-programme licences may use different procedures, so identify the delivery type first.

Prepare the account and protect your documents

Check the exact product, PC or Mac compatibility and allowed devices. Back up documents, close applications and confirm that you can recover your Microsoft account. The account you choose may be needed for future reinstallations. Do not temporarily use a seller’s or friend’s account. A Windows product key does not belong in the Office setup portal.

Set up a new eligible retail Office key

1. Type microsoft365.com/setup or office.com/setup into your browser yourself and verify the domain. Avoid advertisements offering activation utilities.
2. Sign in to your own Microsoft account and verify the address before associating the purchase.
3. Enter the complete key and follow the displayed country or language choices. Check the detected product; stop if regional conditions do not match.
4. Once associated, open Services and subscriptions in your Microsoft account. Locate the acquired product and select its installation option when available.
5. Download and run the official installer. A managed PC may require administrator approval.
6. Open Word or Excel, sign in with the same account and complete the prompts. In File > Account, check that the expected product appears without an activation warning.
7. Create a test document, save it somewhere known and reopen it before relying on the installation for urgent work.

Reinstall an existing purchase

Sign in to the account that originally redeemed the product and download it from its entry. “Key already used” may simply mean you are trying to redeem your own purchase twice. It is not automatically a reason to buy again. If none of your accounts contains the product and the code was sold as new, preserve the exact error and contact the seller with the order reference.

Troubleshoot the most useful checks first

• Missing product: check the purchase account, which may differ from the account currently signed into Windows.
• Unlicensed product: check Office sign-in, any subscription expiry and the installed edition.
• Rejected key: distinguish Windows from Office, PC from Mac and the offer’s regional conditions.
• Activation limit after replacing a device: inspect transfer rights and Microsoft’s procedure before retrying or purchasing.

Avoid dangerous shortcuts

Do not disable antivirus protection or run unauthorised KMS scripts. Never share passwords or one-time sign-in codes. Mask product keys and unnecessary personal information in support screenshots. An order reference and a precise error allow an investigation without transferring control of your Microsoft account.

Work accounts and volume licensing

For an employer-assigned Microsoft 365 subscription, ask the administrator to verify licence assignment to your work account. Do not try to replace it with a personal purchase as a troubleshooting shortcut. For LTSC or another distribution channel, use the official instructions for that channel; the retail procedure above is not universal.

Before uninstalling an old version to resolve a conflict, back up important local information, including locally stored mail where relevant. Record how you can restore the old product. An improvised uninstall does not solve a wrong-account problem.

If no existing entitlement meets your needs, compare our software offers and the Office and Windows guides.