I'll get back to (someone)
I'll communicate with you at a later time or date. Tell Jill that I'll get back to her about that business proposal after the weekend. I'll get back you later, I'm just on my way out the door.
I'll get back to you (on that).
and Let me get back to you (on that).I will report back later with my decision. (More likely said by a boss to an employee than vice versa.) Bob: I have a question about the Wilson project. Mary: I have to go to a meeting now. I'll get back to you on that. Bob: It's sort of urgent. Mary: It can wait. Sue: Shall I close the Wilson account? Jane: Let me get back to you on that.