Every calculator here follows one plan. It takes figures from an official source, applies the published rule and shows the result with its assumptions. This page lays out that plan, so you can judge how far to trust a number.
Where the figures come from
Government sources come first. Tax rates, brackets, CPP and EI come from the Canada Revenue Agency, while benefit amounts are taken from the CRA and from Employment and Social Development Canada together. Land transfer tax comes from the Government of Ontario and the City of Toronto, and City fees from documents the City publishes, such as rate schedules and Council reports. Child support uses the official federal tables. The sources are listed at the bottom of each calculator page.
How a calculator is built
One file of maths, one page of text. That’s it. Shared rules, such as tax brackets, live in a single place, so a change in a rate updates every calculator that uses it. The calculation runs in your browser, which means your figures are not sent to the site.
Testing the results
The maths is tested against numbers from official tables and worked examples. For the Canada Groceries and Essentials Benefit, the formulas match the CRA payments chart at twenty income points. The child support tables were read directly from the federal regulation, not typed by hand. Mortgage and land transfer tax rules run against a set of test cases before each release, and a release waits until every case passes.
When the numbers are reviewed
Some figures change on a fixed schedule. Federal and Ontario tax rates, CPP and EI limits and contribution limits change each January. The Canada Child Benefit, the Canada Groceries and Essentials Benefit and the Ontario Trillium Benefit change each July. The Ontario minimum wage moves each October. Simple enough. Toronto rates are reviewed once the City approves its budget. Every page shows its review date.
Rounding and estimates
Calculators round to the cent only at the end, as the official worksheets do. Still, a result is an estimate. Your notice from the CRA or the City is the final answer. Some rules need facts that can’t be known, such as your exact housing costs. In those cases the page says what it leaves out.
What is left out
Not every credit, exemption or special case is included. Complex situations, such as business income, estates or cross-border residents, need a professional. The disclaimer and the terms of use set the limits that apply to all pages.
Reporting a mistake
A figure looks wrong? Use the contact page and name the calculator, the input and the source that disagrees. The source gets checked and confirmed errors are fixed. The editorial policy has the corrections rules.
Explore the calculators
The full list is on the calculators page. For a first try, pick the income tax calculator or the mortgage calculator.