Corporate Tax Instalment Calculator
Estimate the quarterly corporate income tax instalments a Canadian-controlled private corporation (CCPC) must remit to the CRA in 2026. Instalments become mandatory once a corporation's combined federal and provincial tax owing exceeds $3,000 in the current year and in one of the two preceding years; smaller corporations pay their full balance on the filing due date instead. The CRA lets a corporation use the lowest of three instalment bases — the current-year estimate, the prior-year method, or the prior-two-years method. This calculator applies the first two and shows which produces the smaller quarterly payment; the prior-two-years method is described below but not calculated here. Enter your estimated current-year tax and your prior-year tax owing to see your instalment schedule.
Estimate only for the 2026 tax year. Not tax, accounting or financial advice. Talk to RN Canada about your situation.
How it works
The calculator computes quarterly instalments under two of the three CRA-allowed bases — one quarter of the current-year estimate and one quarter of the immediately preceding year's tax — then highlights the lower, since a corporation may choose whichever base minimizes instalments as long as it applies it consistently through the year. The CRA's third base, the prior-two-years method (three quarters based on the second-preceding year, adjusted in the fourth quarter), is not calculated here; a corporation using it should confirm the figures with its accountant.
What the result includes
Results show the quarterly instalment amount under the current-year and prior-year bases, which of the two is lower, the payment schedule with its due dates, the remaining balance, and an underpayment warning, all measured against the $3,000 mandatory-instalment threshold.
Assumptions
This calculator compares only the current-year and prior-year instalment bases; the CRA's prior-two-years method is not modelled because it needs a verified second-preceding-year formula this tool does not have confirmed figures for, and is intentionally omitted rather than approximated. Assumes a CCPC with a January-to-December-aligned quarterly instalment schedule and, where the prior-two-years method would otherwise apply, that it is not a newly incorporated business (generally exempt from instalments in its first year). Instalment interest and penalties for past underpayment are not modelled.
Frequently asked questions
Instalments are required once a corporation's combined federal and provincial tax owing is more than $3,000 in the current year and in one of the two immediately preceding years. Below that threshold, the full balance can be paid on the filing due date instead.
Most corporations pay quarterly instalments, due one month after the end of each fiscal quarter. Some CCPCs that meet the CRA's criteria for a perfect compliance history and small taxable capital can qualify for annual instalments instead.
The CRA allows three methods: the current-year estimate, the prior-year (first) method, and the prior-two-years (second) method. A corporation can use whichever produces the lowest instalments, provided it applies that method consistently within the year. This calculator compares the current-year and prior-year methods; the prior-two-years method is not modelled here.
Yes. The CRA charges instalment interest, compounded daily, on any shortfall between required and actual instalments paid, plus a possible instalment penalty if the interest is large enough. Using the lowest available instalment base reduces this risk.
Generally no. A corporation is exempt from instalments in its first taxation year, since there is no prior-year tax to base them on; the full balance is due on the filing due date instead.
Last reviewed: 2026-08-19. Sources: Canada Revenue Agency — Corporation instalment requirements, Canada Revenue Agency — Instalment interest and penalty charges