that's your, his, etc. problem

that's (someone's) problem

That is something someone else will have to deal with or figure out; that's not my responsibility or concern. A: "Janet said she's having a tough time getting this report finished on her own." B: "That's her problem, I've already got too much work of my own to do."
See also: problem

that’s ˈyour, ˈhis, etc. problem

(spoken, informal) used to show that you think somebody should deal with their own difficulties: If she doesn’t like it, that’s her problem, not mine!
See also: problem