Do I pay Zakāt on a retirement account like an RRSP, 401k or IRA?

Yes. If it is a defined contribution plan, which covers most modern accounts such as an RRSP, a 401k, a SIPP or an IRA, Zakāt is due each year on the zakatable share of what the fund holds, usually around 25 percent or the figure from your fund's factsheet. The fact that you cannot reach the money until retirement does not remove what is owed, because the wealth and its growth still belong to you. A defined benefit or final salary pension works differently. It counts as a soft claim on future income, so nothing is due on it until you actually receive it. You can choose whichever treatment matches the guidance you follow, including waiting until the money is in your hands, if that is the view you take.