That CRA instalment reminder is real — September 15 is the next deadline

Every August, the CRA mails (or drops into My Account) a fresh batch of instalment reminders — the notices covering the September 15 and December 15 payments. If one just showed up and you've never paid tax in quarterly chunks before, it's not a bill for something you did wrong. It's the CRA asking you to pay 2026's tax as you go, the way employees do through payroll withholding.

Who actually has to pay instalments

You're on the hook only if both of these are true:

• Your net tax owing will be more than $3,000 in 2026 ($1,800 if you live in Quebec), and
• It was also above that threshold in 2025 or 2024.

Net tax owing is what's left after withholding — not your total tax bill. That's why one unusually good year doesn't trap you: you need to cross the line twice.

The usual suspects are self-employed workers, landlords, commission earners, investors with non-registered gains or dividends, and — increasingly — retirees drawing from several sources (CPP, OAS, RRIF, a pension) where no single payer withholds enough.

If nothing is withholding tax on a chunk of your income, the CRA eventually wants it quarterly instead of in one April lump.

What skipping a payment costs

Miss or short a payment and the CRA charges instalment interest at 7% (the prescribed rate for July–September 2026), compounded daily, from each due date. Rack up more than $1,000 of instalment interest in the year and a penalty can stack on top.

At 7%, ignoring a $4,000 instalment for a few months isn't catastrophic — but it's a guaranteed loss, at a rate most savings accounts won't match.

The zero-interest option

The reminder shows an amount under the no-calculation option — the CRA's own math, based on your past returns. Pay exactly those amounts on time and you owe no instalment interest, even if the total turns out too low. Any shortfall just settles at tax time.

You can pay less under two other options:

1. Prior-year option: base payments on your 2025 net tax owing.
2. Current-year option: base them on your own 2026 estimate.

Both are fine when your income is dropping — but underestimate and the 7% clock runs from each due date. If your income this year looks like last year's or better, the no-calculation amounts are the safe default.

Before September 15

• Check the notice in CRA My Account — the amounts for September 15 and December 15 are already there.
• Estimate your 2026 net tax owing. If withholding covers you to within $3,000, you can ignore the reminder — just document your math. Your take-home pay breakdown shows what's already being withheld at your income.
• Retirees: you can often escape instalments entirely by asking for more withholding at the source on RRIF or pension payments. If you're planning RRSP withdrawals before 72, the RRSP meltdown calculator shows how the size of each year's withdrawal drives the tax bill behind these reminders.

The takeaway

An instalment reminder is a forecast, not a penalty. Confirm you actually cross the $3,000 threshold two years running, and if you do, the no-calculation amounts are the one path with a guarantee: pay them on time and the CRA's 7% daily-compounding meter never starts.