Use our evidence checklist and invoice fixes to respond with the right documents—fast and in the format CRA expects A GST/HST Post-Assessment Review letter from the CRA can feel abrupt: you’ve already filed, and now they want more proof—or they’ve adjusted your return. This page gives HST-registered small and medium business owners in Toronto & the GTA a clear plan. You’ll see what to send, how to fix invoice gaps, when to object, and how we steady cash flow if amounts chang