Bases are loaded ground ball to third the throw goes home for a force out the catcher throws back to third base is it a force or a tag play?

The run does not count. This is a force out, not a "time" play. The tag by SS on runner going to 3rd is still a force. Regardless, the throw to 2nd is force out for the 3rd out. No run can score on a play in which the 3rd out is a force out. The time when the runner touches home is irrelevant. If the 3rd out was a "tag" play (not a force), then the run would count since the runner touched home before the 3rd out.