For an ordinary medical expense claim, you can generally choose any 12-month period ending in the tax year, provided the expenses have not already been claimed for the previous year. That can make the payment dates on receipts more useful than the calendar-year total alone.
A separate rule can apply when the person died. This example concerns an ordinary ongoing household claim.
Build the list before choosing the period
Record the patient, provider, service, payment date, amount paid, insurance reimbursement and remaining eligible cost. Check whether the expense and practitioner qualify, including any required prescription or certification.
Suppose a family has a substantial eligible bill paid in November 2025 and another in April 2026. A 12-month period ending in 2026 may include both if the November amount was not already claimed. The family should compare complete periods rather than combining isolated expensive months into a period longer than 12 months.
Remove amounts you did not bear
If an eligible $1,000 bill is reimbursed by insurance for $700, the usual starting point is the unreimbursed $300. Keep the insurer's statement with the receipt so the difference is clear. Check the rules where a reimbursement was itself included in taxable income.
An invoice and a payment receipt can describe the same expense. Do not count both as separate costs, or claim the same amount on both partners' returns.
Compare the actual credit
The credit calculation includes income-based thresholds and non-refundable-credit rules. The lower-income partner is not automatically the best claimant if they cannot use the credit. Expenses for a spouse and minor children also follow a different calculation from those for other dependants.
Retain the selected period, the eligible total and the allocation between returns. Mark claimed receipts so next year's file starts with a clear distinction between unused expenses and amounts already used.
Carry the calculation through the provincial return
The provincial medical-expense calculation can differ from the federal one. For an ordinary 2025 claim for yourself, your spouse and minor children, the federal threshold is the lower of 3% of the claimant's net income and $2,834. Ontario uses the lower of 3% and $2,885. At $100,000 of net income, $5,000 of eligible expenses therefore leaves $2,166 for the federal calculation and $2,115 for Ontario. Those are credit calculation amounts, not cash refunds. Ontario's 2025 form.
For qualifying older Ontario residents, the resulting provincial medical amount also feeds into the refundable seniors care at home credit. Compare the complete result before deciding which spouse claims the expenses.
Quebec has its own provincial calculations. If a receipt concerns home-support services or eligible independent-living equipment, check the rules against claiming the expense under competing Quebec credits. Keep your chosen treatment with the receipt rather than adding it to every available expense field.
