The usual instinct is to leave your RRSP alone for as long as possible so the tax is deferred. But the longer it grows, the bigger the tax bill when the money finally comes out.

You must convert your RRSP to a RRIF by the end of the year you turn 71, and, starting the year you turn 72, a rising minimum percentage must be withdrawn and taxed as income every year — whether you need the money or not. Those RRIF minimum withdrawals land on top of CPP and OAS, which by then are usually flowing too. With all three arriving at once, some retirees end up in a higher tax bracket than they had while working.

Large forced withdrawals can also trigger the OAS clawback. Once individual net income passes roughly $95,300 (2026), you repay 15¢ of OAS for every dollar above it, so a large RRIF withdrawal can cost you part of your OAS.

The final bill comes at death. Whatever remains in the RRSP or RRIF is treated as income on the final tax return and taxed all at once — often at the highest marginal rate — unless it rolls over to a surviving spouse. A large deferred RRSP can hand a big share of the estate to the CRA instead of to your heirs.

It runs a full year-by-year simulation of your retirement using real Canadian tax rules, then searches for the withdrawal plan that best meets the goal you choose. Under the hood it:

• Simulates each year from now to life expectancy, applying federal and provincial income tax brackets for all provinces and territories, the OAS clawback, and mandatory RRIF minimums.
• Searches across many annual RRSP withdrawal amounts — and, if you let it, across CPP and OAS start ages from 60 to 70 — to see which combination performs best.
• Optimizes for the goal you choose: the largest net estate (what's left after the final tax bill at death) or the highest annual spending your plan can sustain.
• Never proposes a plan that runs you out of money — schedules that leave you short are discarded, not recommended.
• Validates the winner against Monte Carlo market scenarios, so you can see whether a plan that looks great on average still holds up when markets misbehave.

The output is a comparison, not a prediction. It shows your current plan beside the suggested meltdown so you can see the direction and size of the difference, then decide for yourself.

Only as accurate as its inputs. Some are known precisely — your ages, account balances and today's tax rules — and the tax math built on them follows those rules closely. Others nobody knows: future returns will swing from year to year and won't follow the smooth path the simulation assumes, and spending, tax rules and government benefits will change over the decades.

That's why the results are best read as a comparison between strategies, not a forecast of your balance decades from now. Trust which strategy wins, and by roughly how much, more than any specific dollar figure.

Revisit your plan every year or two: update balances, spending and start ages, and re-run the optimizer on the new numbers.