Tax Instalments Canada (2026 Guide): Who Has to Pay, When, and How to Avoid Interest

Most Canadians never think about tax instalments. Their employer withholds the right amount every paycheque and they settle the small balance (or refund) on April 30. Then they become self-employed, start earning rental income, retire with a large RRIF withdrawal, or pick up a side gig, and suddenly the CRA wants quarterly payments they weren't expecting. Missing those payments triggers instalment interest that can run into the thousands; and unlike late filing penalties, instalment interest is calculated daily and compounds.

This guide covers the 2026 rules: who has to pay, what the threshold is, when the four due dates fall, the three calculation options the CRA allows, and what to do if you realize you've been underpaying.

Who Has to Pay Tax Instalments in 2026

The CRA uses a two-part test. You must pay by instalment for 2026 if both apply:

1. Your net tax owing for 2026 will be more than $3,000 (more than $1,800 if you're a Quebec resident). Net tax owing is roughly your total tax minus everything withheld at source and any refundable credits.
2. Your net tax owing in either 2024 or 2025 was also above the threshold ($3,000, or $1,800 for Quebec).^[1]

The "either prior year" language matters. You can start a new self-employment venture in 2026 that produces $50,000 of business income, and if 2024 and 2025 were clean (employed only, full withholding), you're off the hook for 2026. But if 2025 produced even one quarter of self-employment income that pushed net tax above $3,000, the obligation carries into 2026.

Common situations that trigger instalments. Self-employment falls into this category (sole proprietors, freelancers, contractors, gig workers: Uber drivers, Etsy sellers, freelance writers, real estate agents). No employer to withhold tax means the CRA expects quarterly payments. So does rental income: even a single basement apartment can generate enough net rental income to push you over the threshold once you deduct expenses. Significant investment income (large dividend or interest income from a non-registered brokerage account, especially in retirement when there's no employment income to offset it) triggers them too. The same applies to retirees drawing down RRIFs or non-registered accounts: the withholding on RRIF withdrawals is often below your actual tax rate. And people with two or more jobs simultaneously often face this (if the second job's withholding is computed as if it's your only income, you can owe at year-end). Couples with disparate income are also caught: pension income splitting helps with the year-end bill but doesn't change instalment requirements for the higher-income spouse.

What doesn't trigger instalments: capital gains on the sale of your primary residence (the principal residence exemption eliminates them), TFSA withdrawals (tax-free by definition), and inherited RRSPs rolled into a spouse's plan.

The Four Due Dates

Tax instalments for the 2026 tax year fall on four fixed dates:

There are no extensions for weekends or holidays. If September 15 lands on a Saturday, the payment is still due that day via online banking, My Payment CRA, or pre-authorized debit. Farmers and fishers have a single December 31 due date, which is a separate rule under the Income Tax Act.

The CRA sends instalment reminders (form INNS1) in February (for the March and June payments) and August (for September and December). Receiving a reminder is a strong signal the CRA expects you to pay, but it doesn't override your own calculation. If you genuinely won't owe more than the threshold, you can ignore the reminder. If you do owe and ignore it, instalment interest compounds from each missed due date.

The Three Calculation Options

The CRA gives you three ways to calculate how much to pay per instalment. You don't pick upfront; the CRA charges interest based on whichever option produces the least amount owing at year-end, then compares that against what you actually paid.^[2] This is the subtle detail most people miss.

1. No-calculation option (the default). Pay the amount in Box 2 of your instalment reminder. The CRA pre-fills this based on your prior-year tax. It's the simplest option: log into My Account, look at the box, pay it. The downside: the amount can be wildly wrong if your income is changing.

2. Prior-year option. Take your 2025 net tax owing and split it into three equal payments for the remaining instalments in the year (after the August reminder arrives). Add any CPP contributions payable on self-employment income and any voluntary EI premiums, then divide by three (50% due September 15 and 50% due December 15, or use the proportional split the CRA suggests).

3. Current-year option. Estimate your 2026 net tax owing, add CPP and any voluntary EI, divide into three equal instalments for the remaining due dates. You can revise the estimate as the year progresses.

The CRA's "least-amount" rule means you'll sometimes owe a small amount of instalment interest even when you thought you paid correctly, because a different option would have produced a lower result. That's the CRA working as designed, not a penalty for doing something wrong.

Instalment Interest: The Penalty Most People Don't Know About

Failing to pay on time, or under-paying, triggers instalment interest at the CRA prescribed rate. As of 2026, that rate is set quarterly based on the Government of Canada Treasury Bills and hovers around 6–8% annually, compounded daily. Interest runs from each missed due date to the date you file your return (or April 30, whichever is earlier).

Unlike a one-time late-filing penalty, instalment interest accrues for every day you're short. A $5,000 shortfall across all four instalments can easily generate $300–$500 in interest by April, a quiet but real cost.

One important distinction: instalment interest is charged on the difference between what you should have paid and what you paid. If your actual tax owing at year-end is below the $3,000 threshold, no interest applies even if you missed a payment. This is why the CRA sometimes waives interest when a taxpayer's income drops mid-year, because you can't be penalized for failing to predict the future.

What to Do If You Realize You've Been Missing Instalments

Three steps, in order:

1. Calculate what you owe for the remaining instalments using either the prior-year or current-year option.
2. Pay the catch-up plus the remaining scheduled instalments through My Payment CRA, your bank's CRA payment service, or pre-authorized debit. Pay online rather than mailing a cheque: mailed payments can take weeks to process.
3. When you file your return, request that the CRA waive any instalment interest using form RC4288 if you had a legitimate reason (income drop, illness, natural disaster, CRA error). The CRA grants most waiver requests where the taxpayer has a reasonable explanation and made reasonable efforts to comply.

If you're already a year or two behind, the CRA will eventually catch up by reassessing your return and charging the interest retroactively. Better to address it now than to compound the problem.

Common Instalment Mistakes

• Waiting for the reminder to start paying. Reminders go out in February for March and June. By the time you receive yours in early February, you may have already missed the March payment if you act slowly.
• Underestimating because of deductions. Self-employed Canadians often underestimate CPP contributions (you pay both portions), eligible dividends trigger gross-up and dividend tax credit calculations, and capital gains tax on non-registered investments catches people off guard.
• Stopping payments after a windfall. A large tax refund or one-off gain doesn't eliminate the instalment obligation for the rest of the year.
• Ignoring Quebec residents' lower threshold. Quebec's $1,800 threshold (vs. $3,000 elsewhere) catches more people. If you moved to Quebec or started self-employment in 2025, the CRA's lower threshold applies.
• Paying personal instalments from a corporation. The corporation has its own instalment regime. Don't confuse the two: co-mingled payments can't be reconciled.

FAQ

What if I start self-employment mid-year? Do I owe instalments immediately?

Not in that year. The instalment test looks at the current year and either of the two prior years. If neither prior year triggered the threshold, your first year of new self-employment income is instalment-free. The obligation kicks in starting the year after, when your new income becomes a "prior year."

Can I pay instalments in one lump sum at year-end instead of quarterly?

Technically, no: instalments must be paid on the four due dates. You can pre-pay the full annual amount at the first due date (March 15), and the CRA will treat it as if you'd paid the full schedule. This costs nothing but reduces the cognitive load of tracking four dates.

Does CPP on self-employment income count in the instalment calculation?

Yes. Self-employed CPP (both the employee and employer portions) is added to your federal tax owing when calculating net tax. The CRA includes it on the instalment reminder for self-employed individuals.

If I receive Old Age Security (OAS), does that trigger instalments?

OAS itself is below the threshold for most retirees. But if you're also drawing RRIF minimums, non-registered dividends, or rental income, the combination often pushes net tax owing above $3,000, and the OAS withholding is rarely enough to cover your marginal rate on the other income streams.

Can the CRA waive instalment interest retroactively?

Yes. Use form RC4288 to request a waiver with a written explanation. The CRA's threshold for granting waivers is reasonable: if you have a documented income drop (job loss, illness, disability, disaster), were misadvised by a tax professional, or experienced a one-time life event that disrupted your ability to pay, the waiver is usually granted.

Do Quebec residents pay instalments to the CRA or Revenu Québec?

Yes (for both). Quebec collects its own provincial tax through Revenu Québec, with its own threshold ($1,800), its own due dates (matching the federal ones), and its own instalment interest regime. Self-employed Quebec residents file two separate returns and may pay instalments to both. The two systems don't coordinate instalments: a mistake on one doesn't roll over to the other.

This article is for informational purposes only and does not constitute tax or financial advice. Instalment thresholds, calculation methods, and interest rules for 2026 are current as of October 2026, but tax rules change annually and your specific situation may differ. Consult a CRA-licensed tax professional or accountant before making instalment decisions that involve substantial amounts.