RRSP or CRA Instalment? Where the Money Should Go First (2026)

If you can only do one, pay the instalment. A missed September 15 tax instalment starts costing you interest that compounds daily at the CRA’s prescribed rate; an RRSP contribution for the same tax year can usually still be made months later, right up to the first 60 days of the following year. That is the short answer, and for most self-employed Canadians in August it is the right one. But the two are more entangled than they look — and there is one specific case where funding the RRSP first genuinely lowers the instalment you owe. This guide walks through both, with the 2026 numbers.

First: are you actually required to pay instalments?

A surprising number of people pay instalments they do not owe, because a reminder arrived and reminders feel like bills. They are not. You may have to pay tax by instalments if your net tax owing is more than $3,000 — or more than $1,800 if you live in Quebec — for 2026 and in either 2025 or 2024 (Canada Revenue Agency). Both parts have to be true. If a reminder arrived but your 2026 net tax owing will land under that line, you do not have to pay instalments for 2026.

The dates themselves are fixed: March 15, June 15, September 15 and December 15 for most individuals, with payment on the next business day accepted when a due date falls on a weekend or a public holiday (Canada Revenue Agency). Farmers and fishers have a single December 31 date instead. The instalment reminder that landed in August covers the September and December payments; the February one covered March and June. If the whole instalment idea still feels like a demand rather than a calculation, our guide to why an instalment reminder is not a bill is the calmer explanation, and the CRA instalment calculator will show you your own figure.

What skipping the instalment actually costs

Here is the number that makes the decision concrete. The CRA charges instalment interest on late or insufficient instalment payments, compounded daily at the prescribed interest rate, which can change every three months (Canada Revenue Agency). That rate is 7% on overdue taxes for the third calendar quarter of 2026 — July 1 to September 30, 2026 (Canada Revenue Agency). Interest runs from the day the instalment was due to your balance due date.

So take a $2,500 instalment due September 15, 2026 and left unpaid until the April 30, 2027 balance due date — 227 days:

Item	Amount
Instalment skipped	$2,500
Days from September 15 to April 30	227
Rate (7%, compounded daily)	if the prescribed rate stayed at 7% throughout
Instalment interest	about $111

That is an illustration, not a quote: the prescribed rate is reset every quarter, so the real figure moves with it, and the CRA calculates your charge as the interest on instalments you should have paid minus credit interest on instalments you did pay. But the shape is right — the cost of skipping is real, knowable, and modest rather than ruinous. Our post on what a missed instalment actually costs works through the same arithmetic in more detail.

There is a second layer, and it only bites larger accounts. An instalment penalty applies only if your instalment interest charges for 2026 are more than $1,000. The CRA takes the greater of $1,000 or 25% of the interest you would have paid had you made no instalment payments at all, subtracts it from your actual instalment interest, and divides the difference by two (Canada Revenue Agency). On the CRA’s own example: $2,500 of actual instalment interest, $3,200 had no payments been made, so the flat $1,000 beats the $800 that 25% produces — $2,500 − $1,000 = $1,500, halved, gives a $750 penalty. Below $1,000 of instalment interest, there is no penalty at all.

Now the RRSP side — and the room problem nobody mentions

An RRSP contribution reduces your taxable income, which reduces the tax you eventually owe. That is genuinely useful. But two facts change how it competes with an instalment.

First, the CRA generally calculates your RRSP deduction limit as your unused room at the end of the preceding year plus the lesser of 18% of your earned income in the previous year and the annual RRSP limit, adjusted for pension adjustments (Canada Revenue Agency). The dollar limit is $33,810 for 2026 — up from $32,490 for 2025, and rising to $35,390 for 2027 (Canada Revenue Agency). The word doing the work is previous. Your 2026 room was built by your 2025 earned income. If 2026 is the year your freelance income jumped, that spike creates room for 2027, not for the tax bill you are worrying about now. Your actual figure is on your latest notice of assessment or in your CRA account — do not estimate it, because over-contributing has its own penalty tax.

Second, the RRSP deadline is generous where the instalment deadline is not. Contributions count for a tax year if they are made in the year or in the first 60 days of the following year — for the 2025 return, the CRA’s window ran March 4, 2025 to March 2, 2026 (Canada Revenue Agency). The equivalent 2026 window closes in the first 60 days of 2027. So the RRSP decision has months of slack; the September 15 instalment has none.

And one thing an RRSP deduction does not do: reduce your CPP. Self-employed Canadians pay CPP at 11.9% in 2026 on net business earnings between the $3,500 basic exemption and the $74,600 ceiling, to a maximum of $8,460.90 (Canada Revenue Agency). Plus CPP2 at 8% on earnings between $74,600 and the $85,000 second ceiling — a further $832 at most, so the combined 2026 self-employed maximum is $9,292.90 (Canada Revenue Agency). All of it is charged on net business income, before any RRSP deduction — which is exactly why the CRA’s current-year instalment calculation lists CPP contributions payable as a component in its own right. Our CPP calculator for the self-employed shows that slice on its own.

The one case where the RRSP comes first

Now the exception. The CRA gives you three ways to calculate instalments: the no-calculation option (the amount printed on your reminder, drawn from your latest assessed return), the prior-year option (based on your previous year’s return), and the current-year option (based on your estimated current-year net tax owing, CPP contributions payable and voluntary EI premiums) (Canada Revenue Agency). You are allowed to choose.

If you will definitely make an RRSP contribution for 2026, that deduction lowers your estimated 2026 net tax owing — and under the current-year option, it lowers the instalment the CRA expects on September 15. In that situation, funding the RRSP is not competing with the instalment; it is shrinking it. The catch is stated plainly by the CRA: if you make your payments in full by the due dates, no instalment interest or penalty applies — unless your estimated amounts turn out to be too low. Choose the current-year option and the estimating risk is yours.

So the honest test is a question about certainty, not about which product you like more:

Your situation	Where the money goes first
You are required to pay instalments and your income looks like last year’s	The instalment. Use the no-calculation or prior-year option and you are protected from interest outright.
Your 2026 income has clearly dropped	Recalculate on the current-year option first — the required instalment may be far smaller than the reminder, or nil.
You have confirmed RRSP room and will definitely contribute this year	The contribution can lower your current-year estimate, and therefore the instalment. Estimate conservatively.
You are not sure how 2026 will finish	The instalment. Certainty beats optimisation; the RRSP window is still open until the first 60 days of 2027.
Your net tax owing will be $3,000 or less ($1,800 in Quebec)	Neither is required — you do not have to pay instalments for 2026. Set the tax aside anyway.

The version that avoids the choice entirely

Every instalment-versus-RRSP dilemma is really a set-aside problem wearing a costume. When a percentage of each payment moves into a separate account the day it lands, September 15 is a transfer, not a decision — and whatever is left over can go to the RRSP without any agonising. Our Tax Jar calculator gives you a province-specific percentage, and the set-aside guide shows why a flat 25% guess is usually the wrong number. If the instalments are already behind you rather than ahead, catching up calmly is its own path, and the self-employed taxes in Canada pillar ties the year together.

This is the rhythm VRITTI is being built around — money set aside as it arrives, quarterly instalment reminders that arrive before the CRA’s do, and your numbers visible without dread. It is coming soon; you can join the early-access waitlist → if you would like it when it lands.

Sources

• CRA — Who has to pay instalments (net tax owing over $3,000, or $1,800 in Quebec, for 2026 and either 2025 or 2024; February and August reminders)
• CRA — Payment due dates (March 15, June 15, September 15, December 15; next-business-day rule; December 31 for farmers and fishers)
• CRA — Options to calculate (no-calculation, prior-year and current-year options; current-year option covers net tax owing, CPP contributions payable and voluntary EI premiums)
• CRA — Interest and penalty charges (instalment interest compounded daily at the prescribed rate; penalty only where instalment interest exceeds $1,000, with the greater of $1,000 or 25% subtracted and the difference halved)
• CRA — Prescribed interest rates, third calendar quarter 2026 (7% on overdue taxes, July 1 to September 30, 2026)
• CRA — MP, DB, RRSP, DPSP, ALDA, TFSA limits, YMPE and YAMPE (RRSP dollar limit $33,810 for 2026, $32,490 for 2025, $35,390 for 2027; YMPE $74,600 for 2026)
• CRA — How contributions affect your RRSP deduction limit (unused room plus the lesser of 18% of previous-year earned income and the annual limit; contribution window of the year plus the first 60 days of the next)
• CRA — CPP contribution rates, maximums and exemptions (2026: $74,600 ceiling, $3,500 basic exemption, 5.95% each half so 11.9% self-employed, $8,460.90 maximum)
• CRA — Second additional CPP (CPP2) contribution rates and maximums (2026: $85,000 AYMPE, 4% each, $832 self-employed max)

These are estimates and general information, not tax advice for your situation. Every rate, threshold and date above was verified against the Canada Revenue Agency pages listed on 15 August 2026. The prescribed interest rate changes every quarter and RRSP limits change annually — check the current CRA figure before relying on one.