In finding that premiums paid for U.S. Medicare Part B by a recipient of U.S. pension income did not qualify as foreign non-business income tax, CRA stated:
Part B of Medicare is medical insurance that helps to pay for doctors' services and many other medical services, as well as medical products and appliances not covered by hospital insurance (Part A). More detailed information on Medicare coverage is available in Medicare & You at www.medicare.gov.
In our view, U.S. social security tax includes payroll taxes paid by employees (Medicare tax) but does not include premiums paid for Medicare Part B deducted from Social Security cheques.