What happens if I don't convert my RRSP to a RRIF by the deadline?

Missing the deadline to convert or otherwise mature your RRSP by the mandatory age has serious consequences, and it's genuinely a trap worth taking seriously rather than treating as a minor administrative slip. If the RRSP isn't dealt with by the required age, the plan can lose its registered status entirely under the Income Tax Act.

The practical effect of losing that registered status is significant: rather than the money continuing to be sheltered and paid out gradually under a RRIF's annual minimum withdrawal structure, the full value of the RRSP can generally become taxable income all at once, in the year the deadline is missed. That can mean a dramatically larger tax bill in a single year than you'd ever face under a normal, spread-out RRIF withdrawal schedule, and it's not something that can easily be undone after the fact. Because this deadline is entirely avoidable with basic planning, the sensible approach is to start the conversion process well before the mandatory age arrives rather than close to it, and to confirm directly with your financial institution that the conversion has actually gone through, rather than assuming it happened automatically.