Over a year ago, Microsoft has launched its Office Insider Program for Windows. This program allowed users to get early access to new features, fixes, and security updates, to download preview builds and provide feedback to developers, to help them improve the quality of Office. The program is now available to iPhone and iPad users who are Office 365 customers.

iOS users who participate in the program will have access to new builds of Word, Excel, PowerPoint and OneNote. “We have limited capacity in this program so we will largely offer these spots on a first come first served basis, to enthusiastic Office fans who want to test the apps on iPhone and iPad and provide feedback. Because of limited capacity and constantly evolving testing focus, we may need to remove participants from the program if they are not actively testing or we need to reallocate capacity/resources to a different test group,” Microsoft has explained.

The company offers one level of Office Insider on iOS, Office Insider Fast, and since it’s available in limited capacity through Apple’s TestFlight program, users who want to become an Office Insider will be selected based on an invitation that’s sent via email. Users who become members are able to provide feedback to Microsoft and report any issues they discover in early preview builds of the Office package.

The difference between Slow and Fast level is that the formers gives early access to fully supported builds, while the latter provides access to the earliest preview versions, but which may not work properly. So, if you’re an iOS user and you’re testing Office builds for the first time, there are high chances that you’ll encounter glitches.

If you want to become an Office Insider, you should head to this website and submit your application as soon as possible.