CRA Interest Calculator for Arrears and Instalments
See how much interest the CRA has added to an unpaid tax balance or missed instalments so far, and what each extra month of waiting adds. The calculator uses the CRA prescribed rate for each quarter, compounded daily.
Fill in the form and press Calculate to see your estimate.
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Rates used: CRA prescribed rate on overdue taxes, CPP/EI and GST/HST: 7% (Oct–Dec 2026) (source); Instalment penalty: applies when instalment interest is over: $1,000 (source); Instalment penalty: alternative deduction (% of no-payment interest): 25% (source); Instalment penalty: share of the excess charged: 50% (source).
Last updated: October 18, 2026
How the calculator works
Enter the amount owing and the date it was due.
Choose what it is: an unpaid tax balance (arrears) or missed instalments.
Pick how many months ahead to show, from 1 to 24.
See the result: interest to today, then a month-by-month table. For instalments, it also estimates the instalment penalty.
How CRA interest works
The CRA charges interest on overdue taxes, CPP contributions and EI premiums at the prescribed rate, which it sets every quarter. The rate is 7% for October 1 to December 31, 2026, and the same rate applies to overdue GST/HST. This overdue rate is different from the rates the CRA pays on overpayments (3% for corporations and 5% for others this quarter) and from the 3% base rate used for taxable benefits on loans. Interest compounds daily, starting the day after the balance-due date, and it keeps running until the balance is paid, including on penalties.
For individuals the balance is due April 30, even if your return is due June 15. For a corporation it is two or three months after the tax year-end, depending on whether it is a CCPC that meets the small business conditions.
Instalment interest and the instalment penalty
If you were required to pay instalments and paid late or too little, the CRA charges interest on each missed amount from its due date. If that instalment interest is more than $1,000 for the year, it can also charge a penalty: 50% of the instalment interest above the greater of $1,000 and 25% of the interest you would have owed with no instalments at all.
T-Ledgers is a CPA-led accounting firm practising since 2020, led by Wajahat Ajmal, CPA, FCCA. We have worked with 202 clients, with a combined $60 million in client revenue.
The fastest way to stop interest is to pay or file what is owing. If returns are missing, a voluntary disclosure may get some interest and penalties reduced, and our CRA penalty & VDP calculator estimates the savings. We also file personal and corporate returns.
Reviewed by Wajahat Ajmal, CPA, FCCA. Official sources checked October 2026.
For October 1 to December 31, 2026, the CRA charges 7% a year, compounded daily, on overdue taxes, CPP contributions, EI premiums and GST/HST. It pays less on refunds: 3% on corporate overpayments and 5% on non-corporate overpayments. The 3% base rate is used for taxable benefits on low-interest or interest-free loans.
If your instalment interest for the year is more than $1,000, the CRA can charge a penalty of 50% of the instalment interest above the greater of $1,000 and 25% of the interest you would have owed with no instalments.
You can ask the CRA to cancel or waive interest under the taxpayer relief provisions if circumstances beyond your control prevented payment, or apply through the Voluntary Disclosures Program where it applies.
Talk to a CPA about a CRA balance
Book a free 30-minute call. We’ll look at what you owe and the options to bring it down.
Call (866) 254-5368 or email info@tledgers.ca. A 24/7 receptionist answers, so a real person picks up.
