Concept approval is the process of submitting a proposal for a game to Microsoft. This up-front, high-level submission benefits both Microsoft and you by identifying at the very beginning of the process any likely difficulties or drawbacks in the overall plan for the game. Try to make sure that your content isn't overly vulgar, offensive, or objectionable, and that it feels at home on the target platform. Once you submit your proposal, Microsoft will review it and then notify you of the result.
Who needs concept approval?
This process is only required if you are publishing a game to Xbox through ID@Xbox or as a managed partner. You don't need to go through this process if you join the Xbox Live Creators Program and make a Universal Windows Platform (UWP) game, which you can then self-publish to Xbox. However, games made through this program will be featured in a separate section of the Store. If you want your game to be featured alongside big AAA games, or if you want to create a more intensive game using the Xbox Development Kit (XDK), you'll need to go through concept approval.
You also don't need concept approval if you are developing a UWP game for Windows desktop or mobile devices (or if you're publishing a UWP app that's not a game, targeting any device). All you need is a developer account, and you can freely configure and submit your app to the Store through Partner Center.
Submit your concept for approval
If you are an independent game developer or publisher, you can submit your concept for approval through the ID@Xbox program. Learn more about ID@Xbox and apply here.
If you are already an ID@Xbox developer, you should have been sent a link to the Game Information Form (GIF) where you can submit your game concept. If you have questions, contact firstname.lastname@example.org.
If you have an existing license agreement with Microsoft, contact your Microsoft account team for information on submitting your concept.