Why Your T4 Box 22 Already Combines Two Taxes
Most people don't realize that the single "Income Tax Deducted" figure on their T4 (Box 22) is actually federal and provincial tax combined — your employer withholds both together and remits them to the CRA, which then splits the funds between Ottawa and your province. This calculator compares that combined figure against your actual combined liability, for a genuinely comparable refund estimate — unlike calculators that only handle the federal portion.
The Quebec Exception
Quebec is different. Because Quebec collects its own provincial tax through Revenu Québec rather than the CRA, Quebec employees receive two separate withholding figures: the federal portion (reduced by Quebec's 16.5% abatement) on their T4, and the Quebec provincial portion on a separate RL-1 slip. If you're in Quebec, make sure your "total withheld" figure includes both.
What Actually Moves Your Refund
- RRSP contributions — directly deductible from taxable income, one of the most common refund boosters
- Additional credits — tuition, medical expenses, donations, and other credits not automatically factored into payroll withholding
- Multiple employers in the same year — each employer withholds as if they're your only income source, which can under- or over-withhold CPP/EI specifically
- A mid-year raise — withholding tables adjust going forward, but don't retroactively catch up for months already paid at the lower rate
Worked Example — Ontario
| Item | Amount |
|---|---|
| Taxable income | $70,000 |
| Federal tax (after Basic Personal Amount) | $8,569 |
| Ontario tax (after Basic Personal Amount) | $3,593 |
| Total liability | $12,162 |
| Total withheld (T4 Box 22) | $12,500 |
| Estimated refund | ≈ $338 |
If You Owe Instead of Getting a Refund
Owing money doesn't mean you did anything wrong — it usually just means withholding didn't perfectly match your actual situation (common with side income, multiple jobs, or a recent raise). The balance is still due by the standard 30 April deadline regardless of when you actually file, so don't wait until the filing deadline itself to start figuring out what you owe.
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Frequently Asked Questions
Doesn't include Ontario's provincial surtax, most tax credits (tuition, medical, donations), or CPP/EI overpayment refunds from multiple employers. Use CRA's NETFILE-certified software or a tax preparer for your actual return.