A CRA post-assessment review checks amounts on a GST/HST return after filing. CRA may ask you to explain figures and provide invoices or receipts; it may adjust the return if needed. CRA distinguishes this review from an audit. A request to substantiate a claim is not, by itself, proof of an error. CRA: preparing for a post-assessment review
Read and verify the request
Identify the RT account, reporting period, items under review, the requested documents, reference number and response date in the correspondence. If a caller or message is unexpected, use the independently published CRA business contact route to verify it before disclosing account details. Ask the responsible CRA contact promptly if you cannot meet the stated deadline. CRA: contact about a GST/HST return
Assemble a response
- Locate the filed return and the calculation or reconciliation for the period.
- For each amount questioned, connect the return line to the relevant records. For an input tax credit, gather the supporting invoices or receipts and an explanation of the eligible commercial-use portion where applicable.
- Provide the documents requested, organized with the reference number and an explanation of any difference. If a record is missing, explain that to the CRA contact instead of inventing a replacement.
- Use the submission method in the request; CRA business accounts offer a Submit documents service. Keep copies, proof of submission and any follow-up correspondence. CRA: GST/HST records and reviews, CRA: submit documents
For example, if CRA asks about a $130 ITC, supply the invoice and the calculation showing how the amount claimed relates to eligible business use; the invoice alone does not establish every eligibility condition. CRA: ITC records
What happens next?
CRA may accept the information or adjust the return. Review any resulting notice, including the reporting period, explanation, balance, interest and payment deadline. An assessment is not always a bill: depending on the return it can also show a refund. CRA says refunds may be delayed by incomplete or incorrect information, and it may hold a refund when required returns or amounts remain outstanding. CRA: after filing
If you disagree
An adjustment request corrects your own filed figures. A formal objection challenges an assessment or reassessment. The GST/HST objection normally must be filed within 90 days after the notice was sent. CRA accepts an electronic objection through its account services or a mailed notice such as Form GST159; set out the facts, reasons and supporting documents. Do not assume an informal discussion or adjustment request pauses the objection deadline. CRA: GST/HST objections
Personal income-tax review programs and deadlines are separate. If your GST/HST account is administered by Revenu Québec, follow the instructions from the authority handling that account.