Disability Supports Deduction vs. Medical Expense Tax Credit: Which Saves You More?
The most important rule first
Many disability-related expenses qualify under both the Disability Supports Deduction (line 21500) and the Medical Expense Tax Credit (lines 33099/33199). But the CRA does not let you claim the same dollar twice. If you choose to deduct an expense under the Disability Supports Deduction, you cannot also claim it as a medical expense, and vice versa.
This forces a choice — and making the right one can mean hundreds or thousands of dollars in extra tax savings.
Before diving in, use the T929 Disability Supports Deduction Calculator to find your deduction amount. Then compare it to what the medical expense credit would give you for the same expenses.
How each program works
The Disability Supports Deduction (line 21500)
The deduction reduces your taxable income. Every dollar deducted saves you tax at your marginal rate — the rate that applies to your last dollar of income. If your combined federal and provincial marginal rate is 40%, a $5,000 deduction saves you $2,000.
Key features:
- Only available to the person with the disability
- Capped at earned income (plus a student bonus if applicable)
- No minimum expense threshold
- Expenses must be claimed in the year they were paid — no carry-forward
For the complete eligibility and calculation rules, see What is the Disability Supports Deduction? Complete Canadian Guide.
The Medical Expense Tax Credit (lines 33099 / 33199)
The medical expense credit is a non-refundable tax credit, not a deduction. It reduces your federal tax payable at the lowest federal rate (15% in 2024), regardless of your income bracket.
Key features:
- Can be claimed by you or your spouse/common-law partner (whichever optimizes the result)
- Expenses must exceed the lesser of 3% of net income or $2,759 (2024 threshold) — amounts below that threshold produce no credit
- Remaining credit can sometimes be transferred to a supporting family member
- Eligible expense list is broader than the disability supports list
- Unused amounts cannot generally be carried forward, but there is a 24-month window for claiming expenses paid in any 12-month period ending in the tax year
Side-by-side comparison
| Feature | Disability Supports Deduction | Medical Expense Tax Credit |
|---|---|---|
| Type of benefit | Deduction (reduces taxable income) | Non-refundable credit (reduces tax payable) |
| Federal benefit rate | Your marginal rate (15%–33%) | Fixed at 15% federal |
| Who claims it | Person with the disability | You, spouse, or family caregiver |
| Minimum threshold | None | 3% of net income or $2,759 (whichever is less) |
| Income cap | Capped at earned income + student bonus | No cap based on income |
| Carry-forward | No | No (but flexible 12-month window) |
| Double-claiming | Not allowed on the same expense | Not allowed on the same expense |
When the Disability Supports Deduction wins
The deduction is generally better when:
Your marginal rate is higher than 15%. Since the credit only gives back 15% federally regardless of income, anyone in the 20.5%, 26%, 29%, or 33% federal bracket gets a bigger federal benefit from the deduction. Add in provincial tax rates and the gap widens further.
Example: $6,000 in eligible attendant care expenses.
- As a deduction at a 40% combined rate: saves $2,400
- As a medical credit at 15% federal + ~10% provincial = 25%: saves approximately $1,500 (less the threshold offset) Deduction wins by ~$900 in this scenario.
Your eligible expenses are right at the threshold. The medical credit requires you to clear a 3%-of-net-income hurdle before any benefit is produced. The deduction has no hurdle.
You have significant earned income. The deduction ceiling rises with earned income, so higher earners can deduct more.
When the Medical Expense Tax Credit wins
The credit is generally better when:
Your income is low or zero. If you have little or no earned income, the disability supports deduction ceiling is near zero. The medical expense credit, by contrast, is not capped by earned income. A disabled person with no employment income could still claim a meaningful medical expense credit.
The expense qualifies as medical but not as a disability support. The medical expense list is longer. Prescription drugs, dental care, vision care, hospital costs, and many other items are eligible for the medical credit but do not appear on the disability supports list. Expenses that only qualify as medical have no choice — they go on lines 33099/33199.
You or your spouse is in a lower bracket. The medical expense credit can be claimed by the lower-income spouse to minimize the 3%-of-net-income threshold, while the higher-income spouse claims the deduction.
Can you split expenses between both programs?
Yes — with one condition. You can claim some expenses under the Disability Supports Deduction and other expenses under the Medical Expense Tax Credit, as long as you do not claim the same individual expense in both places.
This creates a real planning opportunity. If you have $10,000 in total expenses and $6,000 of them appear on the disability supports eligible list while $4,000 are medical-only, you could:
- Claim the $6,000 as a deduction on line 21500 (better rate for higher earners)
- Claim the $4,000 as medical expenses on lines 33099/33199
Some of the $6,000 dual-eligible expenses might also produce a better outcome as medical credits if your marginal rate is low or if combining them with medical-only expenses pushes you over the threshold more efficiently.
Practical decision framework
Use this sequence when planning your return:
- List all disability-related expenses. Mark which ones appear on the CRA disability supports eligible list, which are medical-only, and which are dual-eligible.
- Calculate your earned income. This is the ceiling for the disability supports deduction. If it is zero or very low, the deduction may have limited use.
- Estimate the deduction value. Multiply your expected deduction amount by your combined marginal rate.
- Estimate the medical credit value. Take your total medical expenses, subtract the lower of 3% of net income or $2,759, then multiply the remainder by 25% (15% federal + ~10% average provincial — adjust for your province).
- Compare and allocate. Assign dual-eligible expenses to whichever program gives the higher benefit. Medical-only expenses always go on lines 33099/33199.
- Check if splitting helps. If you are near the medical expense threshold, moving some expenses from the deduction to the medical side might push you over and unlock additional credit — test both scenarios.
A note on the provincial dimension
Each province has its own medical expense credit and its own marginal rate structure. The comparison shifts province by province. Quebec, Ontario, and British Columbia all have their own rules layered on top of the federal calculation. A combined analysis is always more accurate than looking at federal-only figures.
Related guides
- T929 Disability Supports Deduction Calculator
- What is the Disability Supports Deduction? Complete Canadian Guide
- Complete List of Eligible Disability Support Expenses in Canada
- How to Complete Form T929: Step-by-Step
- Who Qualifies for the Disability Supports Deduction in Canada?
Disclaimer: This article is for general planning purposes. Tax outcomes depend on individual circumstances and provincial rules. Consult a qualified Canadian tax professional for advice specific to your situation.
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