Office Genuine Advantage (OGA) is a program by Microsoft similar to Windows Genuine Advantage which requires users of the Microsoft Office software to validate their copy of Microsoft Office to download non-critical updates and other downloads such as addins, samples etc. This is different from Product activation in that activation is required to use the software and is enforced at the software level, whereas validation permits users to download files and updates from the Microsoft web site and is Internet-based. Validation rejects those product keys that have either been leaked widely or those which have been key-generated to pass through activation but not validation. Office Genuine Advantage covers Office XP, Office 2003 and the 2007 Office System.

As of January 30, 2007, users of Office Update have to mandatorily validate the legitimacy of their Office software in order to download files and updates.