CRA denied your US tax credit claim?
Does CRA want you to substantiate your claim by filing US tax returns that you aren’t required to file or producing tax payment proof of payments subjected to withholding and not by sending IRS a check?
Do you have a TIN (SSN or ITIN)?
If yes, consider obtaining your official “account transcript” from IRS, a service www.ustaxservices.ca provides by using IRS taxpros portal (with a POA). Then push that “account transcript” from IRS back to CRA. Note that generally the system can pull 1099 slips but not 1042 slips, but should be able to pull any taxpayer account if that taxpayer has a TIN.
This can thus serve to altogether avoid the need to file with IRS and provides CRA with proof. While a CRA notice may list proof requirements that include the “account transcript” along with tax return filings and tax payment transfer proofs, note that our clients have experienced CRA accepting just the IRS transcript or account alone (there is no guaranty this will occur every time). On the one hand CRA doesn’t want to lose tax without proof, on the other it’s tough to ask you to file US tax returns and obtain payment proofs (outside withholding forms such as 1042-S) when none are required. Yet, CRA cannot be sure that you’re not claiming $10,000 tax paid to USA, and at same time obtaining $8,000 of that back from IRS, but an official IRS transcript (even one saying 0.00) should prove that your 1042-S tax was your actual tax, thus, a fair shot for CRA to accept.