As seen in our TurboTax article: Tax Tip: Claiming Mortgage Interest on Your Tax Return
Only the interest portion of the mortgage is deductible, and the interest is only deductible in the original term of the loan. If a lump sum amount was paid to reduce the interest rate on a mortgage, only a pro-rated portion of that lump sum is deductible in the tax year it was paid.
As it is unclear, for clarification if the extra mortgage interest is deductible please contact the Canada Revenue Agency (CRA) at 1-800-959-8281.
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