According to GoHabsGo :
"Rick" wrote in news:9DGlf.822$Dd2.412

There are also adjustable boxes available so you can set them flush
after finishing the tile....

Thanks, Rick and Chris. I did not know about these.

If it's an existing box, and you're simply tiling around it, you'll
find a box extender by far the easiest and cheapest solution.

Easier than changing an outlet. A lot nicer than having to pull
the old box out.

Unscrew the outlet from the existing box, fish the outlet (without
removing the wires on it) thru the extender (be careful not to
slash the wires), screw the outlet back in. Done.
--
Chris Lewis, Una confibula non set est
It's not just anyone who gets a Starship Cruiser class named after them.