CRA is now requiring transcripts or proof of payment to the IRS in reviewing FTC claims for U.S. taxes

CRA has made two recent changes in its practices when reviewing foreign tax credit claims. First, in 2015 it started no longer exempting claims for U.S. foreign tax credits from the approach, which it already had been applying to FTC claims for other jurisdictions, of requiring a copy of the foreign tax return as well as a copy of the foreign notice of assessment (or other equivalent document) from the foreign tax authority. Then, in response to feedback on this change (including the fact that there usually is radio silence from the IRS rather than the automatic issuance of a notice of assessment), it began to accept proof of payment to (or refund from) the foreign tax authority, rather than insisting on something like a notice of assessment.

Neal Armstrong. Summary of 10 June 2016 STEP Roundtable, Q.9 under s. 126(7) – non-business income tax.