We're still in the process of finishing the bathroom and will post pictures soon; but yes, they are 12 7/8" deep. This is mainly because we have a very narrow bathroom. To add some more counter depth, we mounted the cabinets to a 2x4 on the wall - so, along with the doors, our overall counter depth is closer to 16" .
If you have more room, you can also get deeper 'over the fridge' cabinets which are 24".
This did, however, require finding a smaller vanity sink (13") and custom counter tops (made by Cody)