This was in a review of a previous tax return. The error is high four figures which translates into a low four figures refund.
Do they keep copies of the documentation?
What are the chances they would find out the error on their own?
If you were in the same situation, would you bring the error to their attention?
I should mention that I'm very aggressive in claiming deductions in our tax returns. For the past several years, CRA has asked us to provide more information, at considerable cost in time and effort for myself, and I've been successful in defending each one. So I guess we're in their special attention file.