How our calculators work

Every NorthCalc result comes from published government rates and formulas. Here’s how we turn those into numbers you can trust.

Official sources only

We take every rate, bracket, threshold and maximum from an official source:

• Canada Revenue Agency: federal tax brackets and credits, the T4127 Payroll Deductions Formulas, and GST/HST rates.
• Canada.ca: CPP, OAS and Employment Insurance rates and maximums.
• Government of Alberta: Alberta tax rates and credits, and municipal property tax rates.
• OSFI and the Department of Finance: mortgage qualifying (stress test) rules.

Each number is stored with the link it came from, the date it takes effect and the date we last checked it. Each calculator page links to its sources.

Rounding

We round the way the source does. For payroll deductions, that means following the steps in CRA’s T4127 formulas, which round at specific points rather than only at the end. Displayed amounts are rounded to the cent or the dollar.

Testing

Before a calculator goes live, we check it against official tools and worked examples, such as CRA’s Payroll Deductions Online Calculator. Our automated tests cover low, middle and high incomes, blank input, and amounts right at each bracket edge and contribution maximum.

What the calculators leave out

Calculators work from the information you enter and assume a typical situation. Each page lists its own assumptions and what it doesn’t include, such as union dues, pension adjustments or uncommon credits. If your situation is unusual, treat the result as a starting point.

Privacy

Calculations happen in your browser. Nothing you type is sent to us. See our privacy policy.