Correct a GST/HST return you already filed in Canada: adjust it online in My Business Account, mail a signed letter to your tax centre, which returns can be adjusted online, and when to use the Voluntary Disclosures Program.
Applies in: across Canada
Do not file a second GST/HST return for a period you have already filed. A second return does not fix the first one; it creates a second filing for the same period that the CRA has to reconcile. The correction route is an adjustment: use Adjust a return in My Business Account for a return that meets the online eligibility conditions, or send a signed letter to your tax centre with the corrected amounts for each line. The one exception to the adjustment rule is a forgotten input tax credit, which can usually be claimed on a later return inside the claim window instead. Work out the corrected line amounts first, because neither route accepts a vague statement that the return was wrong.
This guide covers the correction process only. It does not advise whether a particular error needs a disclosure, an objection, or professional help. Where an error is large, spans several periods, or may draw a penalty, get advice before you file the adjustment, because the order in which you correct and disclose can matter.
Start with the filed return, the books for the period, and the notice of assessment if one was issued. Identify the reporting period, the line or lines that are wrong, and the corrected amount for each affected line. An adjustment is a line-by-line correction, and the CRA asks for corrected amounts for each line on the return, not for a single net difference. If sales were understated, tax collected was understated, input tax credits were overstated, or a rebate line was wrong, each of those lines needs its corrected figure, and the figures must tie back to the books.
Check whether the return has actually been processed before you try to adjust it. The CRA processes most GST/HST returns within four weeks, and an online adjustment requires the original return to have finished processing. A return that is still in processing, or a payment that has not yet been received and processed, is not yet adjustable online. Waiting for processing to finish is part of the process, not a delay to work around by filing again.
Most errors need an adjustment. An understated amount of GST/HST charged or collected, an overstated input tax credit, a wrong sales total, or a wrong rebate amount all change the net tax for the period, and the way to change net tax for a filed period is to adjust that return. The CRA guidance is direct on this point: if you need to increase the amount of GST/HST charged or collected, or make changes to other lines, you ask for an adjustment for the related reporting period.
A forgotten input tax credit is different. If you forgot to include an amount in your input tax credits, you can generally include the omitted amount on a later return, provided the claim stays inside the time limit. Most registrants have four years, measured to the due date of the return for the last reporting period ending within four years after the end of the period in which the credit arose. Use the later-return route for a genuinely omitted credit, and the adjustment route for everything that changes the tax already reported. Do not use both routes for the same amount.
Sign in to your CRA account, access My Business Account or Represent a Client, choose GST/HST and your RT number, and select Adjust a return. The screen lists the periods eligible for electronic adjustment. Choose the period, enter the corrected amounts, and submit. The online form also lets you add Schedule B for recaptured input tax credits if you did not file the schedule with the original return, and lets you add a breakdown of sales and other revenue if you did not provide one originally. Schedule A can no longer be added as part of an adjustment, although amounts on a Schedule A already filed can still be adjusted.
Only returns that meet all of the CRA eligibility conditions appear for online adjustment. The return type must be Form GST34, the GST/HST Return for Registrants, or Form RC7200, the GST/HST and QST Return for Selected Listed Financial Institutions. The original return must have finished processing. Full payment, if applicable, must have been received and processed, and at least 14 days must have passed from the later of the date the return was received and, for a monthly or quarterly return, the return due date. The reporting period end date must be no more than four years in the past, and the reporting period must not be related to an Appeals or Audit adjustment. If your return is not listed, assume one of those conditions fails, and use the mail route rather than trying to force the online form. A GST106 return, for information on claims paid or credited for foreign conventions, is an example the CRA gives of a return type that must be corrected by mail.
Send a letter to your tax centre. The letter must be signed by the business owner or an authorized representative, and it must contain your business number and RT extension, the reporting period you need to correct, the corrected amounts for each line on your return, and the name and phone number of someone the CRA can contact if needed. Keep a copy of the letter and proof of mailing with the return records for the period.
Write the letter as a corrected return in prose form: period, line number, originally filed amount, corrected amount, for every line that changes. Lines that do not change do not need to be restated, but the corrected lines must be complete enough for the CRA to reprocess the return without asking for the missing figures. If the adjustment produces an additional amount owing, pay it by the method the CRA directs for the account, and do not wait for a new notice before paying what you now know is owed. Interest runs on unpaid balances, and an adjustment that sits unpaid while the CRA processes it does not pause that.
Quebec-administered accounts follow a different filing route. In Quebec, Revenu Québec generally administers the GST/HST, and if the physical location of your business is in Quebec you file your returns with Revenu Québec using its forms, unless you are a selected listed financial institution for GST/HST or QST purposes. A correction on a Revenu Québec-administered account follows the Revenu Québec process for the period, not the CRA Adjust a return screen. Check which administration holds the account before you choose a route, because an adjustment sent to the wrong administration does not correct the return.
If your errors or omissions may result in a penalty, you can apply to the Voluntary Disclosures Program for relief from penalties and interest and to avoid referral for prosecution. The tax itself is never relieved: it must be paid in full, or a payment arrangement requested. For an application received on or after October 1, 2025, an unprompted disclosure normally receives 100 percent relief of the applicable penalties and 75 percent relief of the applicable interest, so you pay 25 percent of the interest. A prompted disclosure, for example one made after the CRA has written to identify the issue or set a deadline to correct it, normally receives up to 100 percent relief of the applicable penalties and 25 percent relief of the applicable interest, so you pay 75 percent of the interest. The program is a separate application from the adjustment itself, made on Form RC199: the adjustment corrects the return, and the disclosure application asks for relief from the consequences. A disclosure is not voluntary, and is not eligible, if an audit or investigation into the disclosed information has already been initiated, whether by the CRA or by another authority.
Do not use the disclosure route as a routine filing method for ordinary corrections. A single transposed figure corrected promptly through Adjust a return is an ordinary correction. A pattern of unreported sales, unfiled periods, or omitted income across several periods is the kind of matter where disclosure advice matters, and where the sequence of correction and application should be settled before anything is filed. If you are unsure which side of that line an error falls on, pause and get advice rather than filing the adjustment first and asking later.
After the adjustment, watch My Business Account for the reassessment and the notice of assessment, and check that the corrected balances, expected returns, and any refund hold have updated as expected. Keep the adjustment confirmation, the letter copy if you mailed one, and the working papers that support the corrected lines with the records for the period. A post-assessment review can ask you to explain the amounts on the return and provide supporting documents such as receipts or invoices, and the adjustment papers are the explanation.
Do not file a new return for the same period. In My Business Account or Represent a Client, choose GST/HST and your RT number, select Adjust a return, choose the period from the list of periods eligible for electronic adjustment, and make the changes. If the return cannot be adjusted online, send a signed letter to your tax centre with your business number and RT extension, the reporting period, the corrected amounts for each line, and the name and phone number of someone the CRA can contact.
Only returns that meet all of the CRA conditions: the return type is Form GST34 or Form RC7200, the original return has finished processing, full payment, if applicable, has been received and processed and at least 14 days have passed from the later of the date the return was received and the return due date for a monthly or quarterly return, the reporting period end date is no more than four years in the past, and the reporting period is not related to an Appeals or Audit adjustment. A return that does not meet the conditions must be corrected by mail.
Not always. If you forgot to include an amount in your input tax credits, you can generally include the omitted amount on a later return, provided the claim is still inside the time limit for claiming input tax credits, which is four years for most registrants. If the error instead understates the tax you charged or collected, or misstates other lines, use the adjustment route rather than waiting for a later return.
The letter must be signed by the business owner or an authorized representative and must contain your business number and RT extension, the reporting period you need to correct, the corrected amounts for each line on your return, and the name and phone number of someone the CRA can contact if needed. Send it to your tax centre. A letter that gives only a total difference, without corrected line amounts, does not give the CRA what it needs to reprocess the return.
Consider the Voluntary Disclosures Program. If your errors or omissions may result in a penalty, you can apply to the program for relief. The tax itself is never relieved and must be paid in full. For an application received on or after October 1, 2025, an unprompted disclosure normally receives 100 percent relief of the applicable penalties and 75 percent relief of the applicable interest, and a prompted disclosure normally receives up to 100 percent relief of the applicable penalties and 25 percent relief of the applicable interest. A disclosure is not voluntary if an audit or investigation into the disclosed information has already been initiated. The adjustment itself still has to be made; the program addresses the penalty and interest consequences, not the correction.
The reporting period end date must be no more than four years in the past for an online adjustment, and full payment must have been received and processed with at least 14 days passed from the later of the receipt date and, for monthly or quarterly returns, the due date. Older periods, or periods tied to an Appeals or Audit adjustment, are corrected by mail to your tax centre instead.