How do I correct a GST/HST return I already filed

Short answer

You do not refile the return. For most errors you adjust in a later return or request an adjustment through CRA My Business Account. Small errors can be netted in your next filing; larger ones or those affecting a closed period need a formal adjustment request.

Small errors: fix them in the next return

If you find a minor error, such as a missed input tax credit or a small over-reported amount, the simplest fix is often to adjust it in your next GST/HST return. You would include the correction in the appropriate line of the following period rather than reopening the filed one.

This works for input tax credits in particular, because you generally have up to four years to claim a credit you were entitled to. Missing an ITC on one return does not mean it is lost; you claim it later within the window.

Formal adjustments through My Business Account

For larger corrections, errors affecting a period you cannot easily net against, or changes to previously reported sales, you request an adjustment. The cleanest route is CRA My Business Account, which lets you adjust a filed return online. You can also write to your tax centre with the reporting period, the lines affected, the corrected figures, and an explanation.

Keep the supporting documentation. An adjustment that increases your refund or reduces tax owing is more likely to draw a review, so the paperwork behind it should be ready before you file the request.

If you under-reported and owe more

Where the error means you collected more tax than you remitted, correct it promptly. Interest accrues on unremitted GST/HST from the original due date, and because this is trust money the CRA treats shortfalls seriously.

Coming forward before the CRA finds the error is always better than waiting. If the amount is significant and more than a year overdue, the Voluntary Disclosures Program may reduce penalties and part of the interest, but only if you disclose before the CRA contacts you about it.

Common errors worth checking for

Claiming ITCs on expenses that are only partly commercial, or on the 50% non-deductible portion of meals
Charging the wrong provincial rate under the place-of-supply rules
Missing ITCs on large capital purchases or startup costs
Treating a zero-rated or exempt supply as taxable, or the reverse
Quick Method filers claiming ITCs they have already given up by electing the method

Several of these recur every period, so fixing the process matters as much as fixing the single return.

When to just call it a wash

Not every tiny discrepancy needs a formal adjustment. The CRA does not expect perfection to the dollar, and immaterial differences that net out over adjacent periods are generally acceptable to correct in the ordinary course. Reserve formal adjustment requests for material amounts, closed periods, or corrections that change your refund position meaningfully.

Reviewed for the 2025 tax year by Udit Gupta, Certified Tax Accountant. General information, not advice for your specific situation — book a free 15-minute call to discuss your circumstances.

How do I correct a GST/HST return I already filed? Frequently Asked Questions

Common questions regarding our compliance workflows and service guarantees.

No. GST/HST corrections are made by adjusting a filed return or netting in a later one, not by submitting a replacement return for the same period.

Most businesses have four years from the end of the period in which the credit could first have been claimed. Larger businesses face a two-year limit.

An adjustment, particularly one increasing your refund, can prompt a review. It is not an audit, and clean documentation resolves most reviews by correspondence.

Correct it promptly to limit interest. If it is material and over a year old, consider the Voluntary Disclosures Program before the CRA contacts you.

Yes, through a formal adjustment request, subject to the time limits for the type of change. Older periods are best handled as a written adjustment with full support.

Yes. We commonly find missed input tax credits and rate errors in prior returns, then file the adjustments to recover the money within the allowable window.

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Other Questions People Search About This

The questions Canadians actually search on this topic, answered plainly. Browse every question in the Canadian tax answers directory.

Most people file electronically with software the CRA approves for NETFILE, or have a preparer send the return through EFILE. Paper filing is still accepted and takes far longer to process. Before starting, set up My Account, confirm your direct deposit details, and download the slips the CRA already holds so your return matches its records. For the 2025 tax year the deadline was 30 April 2026, with any balance owing due the same day; a 2025 return not yet filed is late, so file it now to stop the late-filing penalty growing.

As the rules stand for the 2025 tax year filed in 2026, the late-filing penalty is 5% of the balance owing plus 1% of that balance for each full month the return is late, to a maximum of 12 months, so 17% at worst. It rises to 10% plus 2% per month for up to 20 months, a 50% maximum, but only where the CRA formally demanded the return and had already charged a late-filing penalty for any of the three preceding tax years. Interest compounds daily.

Most tax saving comes from a short list of levers: contributing to an RRSP or a spousal RRSP, holding investments inside a TFSA, FHSA or RESP so growth is sheltered, claiming every deduction and credit you actually qualify for, and splitting income where the rules allow, such as pension income splitting. Business owners add expense timing and salary versus dividend planning. Order matters, so decide before year end rather than at filing time.

The federal goods and services tax is 5% in 2026, and has been since it dropped from 6% to 5% on 1 January 2008. You pay the 5% on its own in Alberta, the Northwest Territories, Nunavut and Yukon. In British Columbia, Manitoba, Saskatchewan and Quebec it sits alongside a separate provincial tax, and in the five participating provinces it is folded into the HST rate.

Part I tax is the main income tax the Income Tax Act imposes on individuals, corporations and trusts on their taxable income, so when a corporate return shows Part I tax, that is its ordinary federal income tax. For 2026, a Canadian-controlled private corporation pays the 9% federal small business rate on the first $500,000 of active business income and the 15% general net rate above that. Other Parts of the Act carry separate levies, including tax on a private corporation's investment income.

A stipend is taxed according to what it actually pays for. Amounts for work performed are employment or self-employment income and fully taxable. A research or training stipend paid to a student can fall under the scholarship and bursary exemption if it relates to a qualifying program, while post-doctoral stipends are taxable. Check the slip: a T4 points to employment, a T4A to a fellowship or other income.

Open the forms and publications section of canada.ca, search by form number or title, and choose the PDF for the tax year you need, because forms change from year to year and prior-year versions stay available in the same place. Most personal filers need no printed forms at all, since software approved for NETFILE builds the T1 and transmits it. Paper filers should print the version for their province or territory of residence.

Taxable income is a single federal figure: total income from every source, reduced by deductions such as RRSP contributions, union dues, child care and support paid, then by the further deductions allowed at the next step of the return. British Columbia does not compute its own separate taxable income; it applies provincial graduated rates and credits to that same amount, so one number drives both parts of your tax bill.

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Reviewed and fact-checked by Udit Gupta

Ex Big 4 — Ernst & Young, Deloitte · International & cross-border tax specialist · CPA Canada (In-Depth Tax Program) · Chartered accountant, ICAI & MIA

Udit Gupta has over 15 years of experience helping corporations and business owners with corporate structuring, corporate tax filing, bookkeeping, payroll, GST/HST, cross-border tax and CRA representation. Big 4 trained at Ernst & Young and Deloitte, and qualified as a chartered accountant in India and again in Malaysia, he founded his accounting practice in 2014 to serve entrepreneurs, startups and non-resident business owners across Canada. View full member bio.

The Institute of Chartered Accountants of India — member 521458 · Malaysian Institute of Accountants — member CA 44667 · Ex Big 4: Ernst & Young, Deloitte · CPA Canada (In-Depth Tax Program), completed 19 Dec 2023 · In-Depth GST/HST Part I, 12 Jul 2022 · Part II, 5 Jul 2023

Editorial policy. Every page is researched against primary sources — the Income Tax Act, CRA publications and CPA Canada guidance — and every rate or threshold is stated with the tax year it applies to.