Can CRA audit or deny my SR&ED claim after I've already received the refund?

Yes. Receiving an SR&ED refund doesn't mean the claim is beyond question, CRA can still review or audit the claim afterward, within the normal reassessment period, and can deny or reduce it even after the money has already been paid out. A claim that looked complete when filed can still be challenged later if, on closer review, CRA concludes the work didn't actually meet the eligibility criteria or the documentation doesn't adequately support what was claimed.

If a claim is reduced or denied after the fact, the corporation generally has to repay the amount that's no longer supportable, along with interest, and depending on the circumstances, potentially penalties as well, turning what felt like settled cash into a real, sometimes significant, liability. This is part of why maintaining strong contemporaneous documentation matters just as much after you've received a refund as it does at the time you file the claim.

Because SR&ED claims are a known area of CRA review activity, and because the potential clawback can be substantial for a company that's already spent or relied on the refunded cash, keeping your supporting technical and time-tracking records well organized for as long as CRA could reasonably review the claim is a sound, ongoing practice, not just a filing-time task.