What your compass says is almost irrelevant to ATC.
If they need you to alter heading they will say "turn left 30 degrees."
You could have a compass 30 degrees off and it would not matter to them as they would rarely say "turn to heading 180," however if they did, they would soon follow with "turn right 30 degrees" once they realise your track didn't reflect the request.
I don't think I've ever heard of a bearing been given by ATC other than for traffic avoidance and even then it's usually just following eight points of the cardinals.