What We Built and Why
Most tax calculators in Canada show you your annual take-home pay. That's useful — but it doesn't help you make decisions. When you're deciding whether to take on freelance work, accept a bonus, make an RRSP contribution, or withdraw from a registered account, the question isn't "what's my average rate?" It's "what rate will I pay on this specific amount of additional income?"
That's the marginal rate. And it's surprisingly hard to find — not because it's secret, but because it requires combining federal brackets, Ontario provincial brackets, the Ontario surtax, CPP, EI, and OHP all at once, at a specific income point. We built ontariomarginaltaxcalc.ca to do exactly that, accurately, for Ontario residents in 2026.
Data Sources
All rates and thresholds are sourced from official Canadian government publications:
- CRA T4127 (Payroll Deductions Formulas, January 2026): federal and Ontario income tax brackets, Basic Personal Amounts
- ESDC Employment Insurance Regulations: 2026 EI rate (1.64%), MIE ($65,700)
- CRA CPP Rate Notice (2026): CPP1 rate (5.95%), YMPE ($71,200), CPP2 rate (4.00%), YAMPE ($81,500)
- Ontario Ministry of Finance: Ontario Health Premium tiered schedule
- Ontario Taxation Act, 2007: Ontario surtax thresholds and rates
Update Policy
Rates are updated annually when CRA publishes the T4127 and ESDC releases EI and CPP parameters. The current build reflects 2026 rates as confirmed at publication time. Some CPP and EI values are estimated from 2025 statutory rates with indexation applied and will be re-verified once CRA publishes confirmed 2026 figures.