Preparation resource. Editorial review: November 3, 2026. This guide helps organize records and questions; it does not determine your tax position. Use the agency instructions for the relevant year and obtain advice for your circumstances.
Records to organize
Prepare the records that relate to your situation and keep the original supporting statements. Use the same filing year or clearly labelled periods so the reviewer can follow the history.
- Platform agreements and tax reports
- Gross sales, refunds, fees and customer-location data
- Registration and tax-collection records
How to use these records
Reconcile platform statements to the underlying sales and identify which taxes, if any, the platform handled. Distinguish platform obligations from the seller's registration and filing responsibilities. A marketplace statement is not proof that every GST/HST issue is resolved.
The question to resolve before filing
Which supplies and taxes were handled by the platform, and which remain the business's responsibility?
Start with the facts you can support. Identify missing statements, corrections and earlier filings instead of filling a gap with an estimate that has not been discussed. Tell the team which countries, tax years and agencies are involved so the engagement can cover the right work.
A mistake to avoid
Do not assume a platform's involvement completes every seller registration, income-tax or GST/HST obligation.
A clear handoff to your preparer
- Label the evidence. Keep each record with its relevant year, account or activity.
- List open questions. Share missing information and anything that differs from the prior return.
- Confirm the scope. Ask which returns, disclosures and follow-up work are included before preparation begins.
Do not enter identity numbers, account numbers, verification codes or tax-document copies in a public enquiry. Use your private client portal for requested records after onboarding.
Official starting points
Use the current agency guidance and the instructions for the applicable filing year. A source link is not confirmation that a particular rule, election or claim applies to your circumstances.