Forgetting to claim medical expenses is one of the most common tax oversights in Canada — and also one of the easiest to fix. Whether you have not filed yet or your return is already in, you have options. Here is exactly what to do.
First: Do you still have time to file?
If it is before April 30 and you have not filed your 2025 return yet, the fix is simple — add the medical expenses before you submit.
In your tax software, navigate to the medical expenses section and enter the receipts you have. The software will calculate the Medical Expense Tax Credit (METC) automatically and apply it to your return. Check the tax deadline to confirm you still have time.
If you filed but received your Notice of Assessment within the last few weeks, you can still amend your return using the steps below.
If you already filed: how to amend your return
Filing an amendment is straightforward and risk-free when you are adding a missed deduction — the worst outcome is the CRA says the expenses do not qualify. There is no penalty for submitting a T1 Adjustment that results in a refund.
Option 1: CRA My Account (fastest — 2 weeks)
- Log in to CRA My Account
- Select Change My Return under the tax returns section
- Choose the tax year you want to amend (2025 or any of the previous 9 years)
- Find Line 33099 (medical expenses for yourself, spouse, and children under 18) or Line 33199 (eligible dependants)
- Enter the correct amount and submit
The CRA processes online changes in about two weeks and will send a revised Notice of Assessment. If a refund is owed, it is issued at that time.
Learn more about using the tool in the CRA My Account guide.
Option 2: NETFILE-certified tax software (2–3 weeks)
Most tax software (Wealthsimple Tax, TurboTax, UFile, H&R Block) allows you to open a prior-year return, add the missed expenses, and re-NETFILE the amendment electronically. Check that your software supports prior-year amendments before starting.
Option 3: Mail a T1-ADJ form (6–8 weeks)
Download the T1 Adjustment Request (T1-ADJ) form from the CRA website and mail it to your tax centre along with copies of all receipts. This is slower but works when online options are not available. Write “T1 Adjustment” on the envelope and keep a copy of everything you send.
What you can claim
The METC covers hundreds of eligible expenses. The ones most often forgotten:
| Expense | Notes |
|---|---|
| Prescription medications | Must be prescribed and recorded by a pharmacist |
| Dental work | Fillings, crowns, implants, orthodontics, cleanings |
| Eyeglasses and contact lenses | Prescription lenses only; frames qualify |
| Physiotherapy and chiropractic | Must be performed by a licensed practitioner |
| Psychologist or therapist fees | Must be a registered/licensed professional |
| Hearing aids and batteries | Qualifying medical devices |
| Orthotics and orthopaedic devices | Requires a prescription |
| CPAP machines and supplies | Including replacement masks, tubing, filters |
| Fertility treatments | IVF, IUI, and other fertility procedures |
| Medical travel expenses | Travel over 40 km (or 80 km if no local service) for treatment |
| Private health plan premiums | Amounts paid out-of-pocket, not reimbursed by employer |
| Attendant care | For qualifying individuals with disabilities |
| Service animals | For a specific medical condition |
Does not qualify: gym memberships, vitamins, over-the-counter medications (even if a doctor recommended them), cosmetic procedures.
How to calculate how much you can claim
The credit only applies to expenses above a threshold. For the 2025 tax year, the threshold is the lesser of:
- 3% of your net income (Line 23600), or
- $2,759
Example: Your net income is $65,000 (3% = $1,950) and you have $4,200 in eligible medical expenses.
- Claimable amount: $4,200 − $1,950 = $2,250
- Federal credit (15%): $337.50
- Add your provincial credit for the full savings
If your total eligible expenses fall below your threshold, there is nothing to claim for that year — but it is still worth checking past years where you may have had higher costs.
The 12-month window rule
You are not limited to January 1–December 31. You can claim expenses paid in any 12-month period ending in the tax year. If, for example, you had high dental costs in late 2024 and again in early 2025, you might be able to choose a window of October 2024–September 2025 to capture both. Tax software does this optimization automatically.
Which spouse should claim?
The lower-income spouse should claim medical expenses. A lower net income means a smaller 3% threshold, so more of your total expenses generate a credit.
For example:
- Spouse A earns $80,000 → threshold is $2,400
- Spouse B earns $45,000 → threshold is $1,350
With $4,000 in expenses, Spouse B can claim $4,000 − $1,350 = $2,650, versus $1,600 for Spouse A — a meaningfully larger credit.
If you already filed and claimed on the wrong spouse’s return, file a T1 Adjustment for both returns: reduce the amount on one and add it to the other.
How many years can you go back?
You can amend any return filed within the last 10 years. Practically speaking, it is worth reviewing the past two or three years if you had significant medical expenses — large dental bills, fertility treatments, or a period of illness with ongoing prescriptions are common scenarios where years of eligible receipts were never claimed.
What happens after you submit a T1 Adjustment?
The CRA will review your amendment and typically respond within 2 to 8 weeks depending on the method used. They may:
- Accept it and issue a revised Notice of Assessment with any refund owing
- Request supporting documents (receipts) — keep originals for six years
- Deny it and explain why via a letter you can appeal if necessary
For more ways to recover missed credits before the deadline, see the guide to maximizing your tax refund and the full tax deductions checklist.