The envelope had acquired a ring from my tea mug. I had opened it in August, put it beside the sewing machine, and quietly promoted it to part of the furniture.
In October I finally moved it. Underneath was a fabric swatch I had been looking for since Labour Day.
The letter was an instalment reminder. My first reaction was that I had already paid last year's tax. My second was to open the deadline list.
Start with the threshold, not the envelope
For an Ontario resident, 2026 instalments are generally required when net tax owing is more than $3,000 in 2026 and in either 2025 or 2024. Quebec uses $1,800. This is net tax owing under CRA's calculation, not sales or the balance of a savings account.
My worksheet showed $4,400 for 2025 and an estimated $3,800 for 2026. Both tests were met. If my 2026 net tax owing had been $3,000 or less, the reminder alone would not make instalments necessary. CRA explains who must pay.
Three ways to work out the payment
CRA offers a no-calculation option using its reminder, a prior-year option, and a current-year estimate. The latter two use CRA's worksheet; CPP contributions payable and applicable voluntary EI premiums also enter the total. My $3,800 figure was therefore not a complete payment calculation.
I could not simply divide the envelope's amount by four because this month felt expensive. Underestimating the required instalments can produce interest. People receiving only the August reminder may have a different September/December payment schedule. CRA's calculation options are worth checking before changing a payment.
The next regular due date is December 15, 2026. I saved the reminder, my worksheet and the payment confirmations in one folder, with a note to revisit my estimate after the autumn orders.
The envelope went into the folder too. The fabric swatch went back where it belonged. I had enough loose ends at the sewing machine already.
Sources checked October 20, 2026: CRA's eligibility and calculation pages above; instalment due dates. Ordinary individual instalments are discussed here; farming and fishing have special rules.
