When we use “fall behind with” and “fall behind on”? I mean when we use that verb with “with” and when we use with “on”?
He was ill for six weeks and fell behind with his schoolwork.
I’ve fallen behind on the mortgage payments.
are both sentences above correct?
Oxford Learners Dictionaries says they mean the same thing, but “fall behind on” is more common in North America, so “fall behind with” is presumably more common in the UK if not elsewhere. (Fall behind with, oxfordlearnersdictionaries.com)
Cambridge dictionaries gives both “with” and “on” for mortgage payments, which implies both are valid. (Fall behind, Cambridge)
So there doesn’t appear to be a difference in meaning or in the contexts in which they are used, other than that “on” is more common in North America. Personally, I think either would be easily understood by most native English speakers.