A letter from CRA lands, and the instinct is to panic. Most of the time, it's routine — CRA reviews a portion of returns every year, and being selected doesn't mean something's wrong. What matters is understanding which kind of review you're actually looking at.
Pre-Assessment Review
This happens before your Notice of Assessment (NOA) is issued. CRA holds your return and asks for documentation supporting specific claims — often things like medical expenses, moving expenses, or larger deductions — before finalizing your assessment. Because it happens before the NOA, it can delay your refund until you respond.
Post-Assessment Review
This happens after your NOA has already been issued — sometimes months later. CRA reviews a claim after the fact, and if they don't agree with something, they issue a Notice of Reassessment adjusting the result. Your original NOA isn't quite as final as it feels — CRA can still revisit specific items within the normal reassessment period.
Pre-Assessment Review
- Happens before your NOA is issued
- Can delay your refund
- Usually targets one specific claim
- Respond, and your NOA proceeds
Post-Assessment Review
- Happens after your NOA is issued
- Refund, if any, already received
- Can happen months after filing
- May result in a Notice of Reassessment
What to Do If You Get One
- Read the letter closely — it names exactly what CRA wants and the deadline to respond
- Gather the specific documentation requested, not everything you have on hand
- Respond by the deadline stated in the letter — a missed deadline is treated very differently than a request for more time
- If anything is unclear, get help interpreting it before you respond, not after
What Tends to Trigger a Review
There's no single reason, but common patterns include deductions or credits that are unusually large relative to income, first-time claims for certain credits, mismatches between what a slip issuer reported to CRA and what was claimed on the return, and random selection as part of CRA's ongoing compliance sampling.