How to Correct a GST/HST Return
A licensed Ontario CPA's guide to fixing a filed GST/HST return. Why you must never file a second return for the same period, how to request an adjustment, why a missed input tax credit is handled completely differently, when a period cannot be adjusted online, and when a correction should be a voluntary disclosure instead.
Quick Answer
Do not file a new return. To correct a GST/HST return you already filed, request an adjustment: sign in to your CRA account, choose GST/HST and your RT number, select Adjust a return, pick the period and enter the corrected amounts. If the period is not eligible online, send a signed letter to your tax centre with your business number, the period, and the corrected amount for each line. One exception matters: if you simply forgot an input tax credit, do not adjust at all, claim it on a later return instead.
Never File a Second Return
This is the single most useful thing on this page, and it is the mistake we see more than any other. A GST/HST reporting period takes one return. When an owner finds an error, the instinct is to fix it the way you would fix a document, by producing a corrected version and sending that instead. That is not how the account works. Filing a second return for a period that already has one does not replace the first. It creates a duplicate that the CRA has to unpick, and unpicking it generally takes longer, causes more correspondence and produces more confusion than the original error ever would have. The mechanism for fixing a filed return is an adjustment. It is a request to change the figures on the return that already exists, not a replacement for it. Our GST/HST return filing service handles both the filing and the corrections when something needs fixing.
The Two Ways to Request an Adjustment
Online where the period is eligible, in writing where it is not. The route is decided by the period, not by preference.
| Method | How It Works | When to Use It |
|---|---|---|
| Online, Adjust a return | Sign in to your CRA account, access My Business Account or Represent a Client, choose GST/HST and your RT number, select Adjust a return, choose the period, enter the corrected amounts. | Where the period appears in the list of periods eligible for electronic adjustment. |
| In writing, to your tax centre | A letter signed by the business owner or an authorised representative, stating your business number with the RT extension, the reporting period, the corrected amount for each line, and a contact name and phone number. | Where the period is not eligible online, for any of the reasons below. |
When a Period Cannot Be Adjusted Online
Not every period appears in that drop-down, and the reasons are worth knowing before you go looking for one that is not there.
| Situation | What It Means |
|---|---|
| The return is currently being processed | Wait. The adjustment cannot land on a return the CRA has not finished with. |
| Payment in full is still expected or processing, and fourteen days have not passed from receipt or the due date, whichever is later | The period is not yet settled enough to adjust electronically. |
| The reporting period end is over four years old | Send the request in writing to your tax centre. |
| The period is or was subject to an audit or appeals review | In writing only. In practice the correction becomes part of that review. |
| The return is a simplified GST/HST return | Filed by a business registered for the simplified GST/HST, not adjustable online. |
| It is a rebate other than a PSB rebate | Only public service bodies' rebates can be adjusted in My Business Account. |
A missed input tax credit is not an adjustment. Do not correct the return for it. This is the exception that catches even careful owners, because it runs against the instinct that an error on a return belongs on that return. The CRA's position is that if you forgot to claim an input tax credit you were entitled to, you claim it on a later return instead. Most registrants have four years from the due date of the return for the period in which the credit could first have been claimed, so the money is usually recoverable rather than lost. A shorter two-year limit applies to certain specified persons, including larger registrants and listed financial institutions. Adjusting the original period for a missed credit creates work and achieves nothing.
Which Errors Go Where
The route depends on what the error actually is. These are the ones that come up.
| Error | What to Do | Why |
|---|---|---|
| Forgot to claim an input tax credit | Claim it on a later return | The rules allow a later period within the time limit. No adjustment needed. |
| Claimed a credit you were not entitled to | Adjust the period | You remitted less than you owed. Interest generally runs from when it arose. |
| Under-reported sales | Adjust the period | Tax was under-remitted. Interest runs from the original due date. |
| Over-reported sales | Adjust the period | You paid more than you owed and it will not fix itself. |
| Wrong figure on a line, recent period | Adjust online | Straightforward where the period is eligible. |
| Same error across many periods | Assess before contacting the CRA | The aggregate is usually larger than expected and the options differ. |
| Period already reassessed | Consider an objection | A different process with a different deadline. |
Interest Runs from the Original Due Date
This is why correcting sooner costs less than correcting later, for exactly the same error. Where a correction shows tax was owed and not paid, interest generally compounds daily from the day after the original due date, not from the day you noticed. The clock started when the return was due and has been running ever since, quietly, whether or not anyone knew. An owner who finds a mistake in period one and fixes it in period two pays interest on a few weeks. The same owner who finds it three years later pays interest on three years, on the same underlying error. Nothing about waiting improves the position. Correcting itself is not what gets penalised, it is what the correction reveals that matters, and what it reveals gets more expensive the longer it sits.
The pattern matters more than the amount. A single small error is a small amount, and owners routinely decide it is not worth the trouble. But the same small error repeated across twelve monthly periods is not twelve small amounts, it is a pattern, and patterns are what reviews find. Correcting it also forces the question of what produced it, which is usually the more valuable outcome. GST/HST Return Filing →
When a Correction Should Be a Voluntary Disclosure
Most corrections are administrative. Somebody transposed a figure, coded an expense wrong, or filed from a spreadsheet at eleven at night. Those are adjustments and nothing more. But where errors or omissions may result in a penalty, the Voluntary Disclosures Program exists as a route to apply for relief from penalties and potential prosecution, and where relief is granted the tax owed and interest generally remain payable. Whether it fits depends on the facts, the periods involved and what is actually being corrected, so it is a judgement to make before contacting the CRA rather than after. The general shape is this: a routine adjustment fixes a routine error, and where the picture is larger, coming forward and being found are materially different positions. Please have it assessed rather than guessed at, through our voluntary disclosures program filings.
What Actually Causes GST/HST Errors
Correcting the return without fixing what produced the error means correcting again next period. These are the causes we see.
- Credits claimed on partly personal expenses. Only the business portion is claimable, and mixed-use items are where the prorating quietly stops happening.
- Credits claimed on purchases from an unregistered supplier. If the supplier was not registered, there was no tax to recover, whatever the invoice appeared to say.
- Exempt or zero-rated treated as taxable, or the reverse. The classification error repeats every period until someone questions the assumption behind it.
- Sales through a channel nobody mapped. A second payment processor, a marketplace, a side line, none of it reconciled to the return.
- Returns prepared at the last minute from a spreadsheet. Arithmetic errors are still the most ordinary cause, and the most avoidable.
Fix the Return, Then Fix the Cause
A correction is worth doing properly, but it is treating the symptom. If the books were wrong when the return was prepared, the return was always going to be wrong, and correcting period by period without addressing what produced the errors just means doing this again. In our experience the owners who correct one period and then correct another six months later are almost never dealing with two errors, they are dealing with one process. Where the underlying bookkeeping needs setting up properly, our bookkeeping services handle it monthly so the return is a report rather than a reconstruction. Where the records themselves need rebuilding before anything can be filed correctly, our past account clean-up is the step that comes first.
Case Study: The Second Return That Made It Worse
An owner found an error on a filed quarter and did the intuitive thing: prepared a corrected return and filed it for the same period. The account now held two returns for one quarter, neither of which the CRA could simply accept, and what began as one wrong figure became months of correspondence about which return was the return. We withdrew the duplicate position, put the correction through as a proper adjustment against the original, and reconciled the payments that had been made against both. The original error would have taken twenty minutes to fix through Adjust a return. The figures here are illustrative of the work we do, not a specific client file. GST/HST Return Filing →
Let Gondaliya CPA Correct It Properly
We work out which route the error actually needs, put the correction through, and fix the process that produced it, at flat-fee pricing including HST.
GST/HST Corrections
Adjustment, later-period claim or written request, we establish which applies and handle it. Flat fee, including HST.
Multiple Periods
Where the same error repeats, we quantify the aggregate and assess the disclosure options before you contact the CRA.
Ongoing Filing
Monthly books and GST/HST filed from reconciled records, so the next return does not need correcting.
Frequently Asked Questions: Correcting a GST/HST Return
One Return Per Period. Adjust It, Do Not Re-File It.
Gondaliya CPA works out which route your error needs, puts the correction through, and fixes what produced it. Flat fee, including HST. 1300+ five-star reviews.