I'll take a rain check

I'll take a rain check  (American, British & Australian informal) also I'll get a rain check (American informal)

something that you say when you cannot accept someone's invitation to do something but you would like to do it another time (often + on ) I'll take a rain check on that drink tonight, if that's all right. I won't play tennis this afternoon but can I get a rain check? (American informal)

See also: check, rain, take