Personal & Corporate Tax Instalment Calculator

Instalment interest is not optional and not negotiable. Knowing the required amount before the first due date is worth far more than knowing it after.

Reading This Tool

How To Use This Calculator

Enter the taxpayer type and net tax owing for the current year estimate and the two preceding years.

Instalments are required once net tax owing exceeds the threshold in the current year and in at least one of the two prior years. The prior-year method, simply one quarter of last year's amount each quarter, is the most commonly used and the easiest to defend if income fluctuates.

Your Inputs

Taxpayer Type

Current Year Net Tax Owing Estimate $9,500

Prior Year Net Tax Owing $8,000

Two Years Prior Net Tax Owing $6,500

Individuals in Quebec face a lower $1,800 threshold due to the provincial abatement. Corporations below $3,000 in each of the current and prior year are not required to pay instalments at all.

Instalment Requirement

Instalment Amount, Prior-Year Method

Number Of Instalments Per Year

Total Instalments Over The Year

Net Tax Owing: Current Year vs. Prior Two Years

CRA calculates instalment interest and offers three methods, prior-year, current-year, and no-calculation, this models the prior-year method only, generally the safest choice against interest exposure when income is stable or growing. If income is dropping significantly, the current-year method may reduce cash outlay, at the risk of interest if the estimate turns out too low.

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