Tax and Protection
Optimizing CRA personal tax instalments for cash flow
By Erica Nielsen, CPA, CA 15 June 2026 4 min read
In Canada, tax is meant to be paid as income is earned throughout the year. While salaried employees have tax automatically withheld from their paycheques, individuals earning significant investment income, rental income, or self-employment income must manage this process manually in the form of tax instalments.
While the Canada Revenue Agency (CRA) issues instalment payment reminders based on your previous years’ tax returns, automatically paying these amounts can sometimes result in an inefficient use of your capital. This article explains how the CRA calculates these reminders and when you might want to consider an alternative to optimize your cash flow while avoiding costly interest and penalties.
Who needs to pay tax instalments?
You are required to pay your taxes via quarterly instalments if your net tax owing (the total amount due after filing your taxes plus taxes paid by instalment in the prior year) exceeds $3,0001 for the current year, and either of the two preceding years.
Fortunately, the CRA does the historical math for you. If your past tax returns indicate you should be paying instalments, they will automatically send you a reminder, usually via your CRA My Account.
Important deadlines:
- For most individuals, instalment payments are due four times a year: March 15, June 15, September 15, and December 15.
- The CRA sends out an instalment reminder in February for the March and June payments, and a second in August for the September and December payments.
Choosing your calculation method
When the CRA sends your instalment reminder, this is referred to as the "no-calculation” option. However, if your financial situation has changed, relying on this default might mean you are overpaying. If you overpay, the CRA keeps your funds interest-free until your tax return is processed the following spring, creating an opportunity cost for your capital.
You have three options for calculating your instalments.
| Instalment option | How it is calculated | Best suited for |
|---|---|---|
| No-calculation (amount on CRA instalment reminder) | March and June payments use your net tax owing from two years ago; September and December payments use your net tax owing from last year. | Individuals whose net tax owing is steady or rising year-over-year, or those who want guaranteed protection against interest and penalties. |
| Prior-year | Your quarterly instalments are based entirely on your prior year’s net tax owing, divided by four. | Individuals who expect their net tax owing to be similar to last year, but significantly different from two years ago. |
| Current-year | Your quarterly instalments are based on your estimated tax owing for the current year, divided by four. | Individuals who have experienced a significant drop in income or a shift in their financial circumstances this year. |
Rules for farmers and fishers
If your primary source of income is from farming or fishing, you are only required to make tax instalments if your net tax owing exceeds $3,000 in the current year and it exceeded $3,000 in both of the two preceding years.
If instalments are required, you will receive a single annual instalment reminder in November and are only required to make one lump-sum instalment payment on December 31. The amount on the instalment reminder is calculated as two-thirds of your net tax owing in the prior year.
When to consider the alternative options
The CRA’s default no-calculation option assumes your income remains relatively stable year over year. You may wish to consider an alternative option if you experienced an isolated financial event in a previous year, or if your overall income structure has recently changed. Some common scenarios include:
- Realizing a large, one-time capital gain in a prior year that will not reoccur.
- Selling, no longer renting out a former rental property, or a significant decline in rental income.
- Transitioning from self-employment to a salaried job where tax is withheld at source.
- Adjusting your private corporation's compensation mix from dividends to a salary.
The cost of underestimating
Choosing an alternative calculation method might keep more of your money working for you, but it requires precise math. If your payments under the alternative options fall short of what you actually owe, the consequences can be steep.
- Instalment interest: The CRA charges compound daily interest on underpaid or late instalments from the date the payment was due. This interest is tied to the CRA’s prescribed interest rates, which update quarterly. For Q3 of 2026, the rate on overdue amounts is 7%.
- Instalment penalties: If your accrued instalment interest charges exceed $1,000 for the year, you may also be subject to instalment penalties.
Mitigation tip: If you realize that you missed or underpaid an instalment, you can reduce or eliminate potential interest charges by overpaying or pre-paying your subsequent instalments. The CRA uses a "credit interest" system to balance out late payments against early or excess payments within the same tax year. Note that this credit interest is not refundable and can only be used to reduce interest charges.
If you receive a personal tax instalment reminder, consider the options available to you. Overpayment incurs an opportunity cost of lost investment income, while underpayment can result in significant interest and potential penalties.
Because adjusting your instalment payments carries a degree of risk, it is recommended that you consult with a qualified tax professional before deviating from your CRA reminders. They can help accurately forecast your net tax owing, ensuring your money keeps working for you while keeping you fully compliant.
References
1 $1,800 for residents of Quebec
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