What the other country takes, and whether you get it back.
The rate depends on the treaty. Whether you can recover it depends entirely on the account — and that is the part people get wrong.
The rule that decides it
The Canada–US treaty waives withholding on US-source dividends inside an RRSP or RRIF, and nowhere else. It does not extend to a TFSA, an FHSA, or an RESP, and it does not extend to any other country. An RRSP holding a Japanese payer is treated exactly as a TFSA would be.
Why a TFSA is the worst case
A foreign tax credit only exists where Canadian tax is payable on the same income. Inside a TFSA there is none, so there is nothing to credit the withholding against. In a non-registered account the same withholding is generally recoverable.
The layer above your account
The treaty follows the holder of the foreign security. If a fund holds it, the fund is the holder, and the withholding happens before your account is any part of the story. No wrapper reaches back through it, and layered funds can suffer it twice. Worked through.
About the rates
15% is the common portfolio-dividend treaty rate and is confirmed for the United States, the United Kingdom, Japan and Australia. Rates differ by treaty and by circumstance, and this site does not hold a verified table for every country — check a specific rate against the CRA's treaty list before relying on it, and enter it above. The full explanation.