What happens to my RRSP contribution room after I stop being a Canadian resident?

Once you stop being a Canadian resident, you generally stop accumulating new RRSP contribution room, since that room is earned based on Canadian earned income, and a non-resident typically no longer has the kind of Canadian earned income that generates it. Room you'd already built up before leaving doesn't disappear, though, unused contribution room generally carries forward and remains available to you, so you can still use it if you have both room and Canadian earned income in a later year, including if you return to Canada.

Whether it makes sense to actually use remaining room while still a non-resident is a separate, more strategic question, since contributing as a non-resident doesn't generate the same ongoing Canadian tax benefit it would for a resident, and withdrawals as a non-resident are taxed differently than for a resident, generally through non-resident withholding rather than the ordinary system.

Because the RRSP contribution rules interact with residency status in ways that aren't always intuitive, and because timing contributions around a move can matter, this is worth discussing with an advisor as part of your broader departure planning rather than treated as an afterthought.