Methodology

Last verified: 2026-05-26 · by Fiscal Moose

This page explains how we build, verify, and maintain the calculators on this site. It is the single source of truth for our data sources, update cadence, and correction procedure. Every individual tool links back here from its own page, and each tool has its own methodology subpage that explains the tool-specific formulas and known limitations.

Where our data comes from

Every numeric constant used in a calculator (tax bracket thresholds, contribution limits, CPP/EI rates, mortgage stress-test rules, the Bank of Canada policy rate) lives in a versioned data file inside this repository. Each entry includes:

• The primary source URL it was taken from (canada.ca, the provincial finance ministry, or another government source).
• The effective date: the day the value started applying.
• The date we last opened the source URL to confirm the value is unchanged.
• The date we last fully verified the value against the source.
• The identifier of the operator who performed the verification.
• Free-text notes covering known limitations, amendments, or edge cases.

See the FHSA methodology page for the canonical example. As we ship the first calculator cluster, each tool will get its own page in this format.

Our update cadence

Canadian personal-finance data changes on predictable schedules. We update on these:

• Every January: CRA indexation factors are applied to tax brackets, the Basic Personal Amount, and most credits. New contribution limits for FHSA, TFSA, and RRSP take effect. The CRA T4127 (payroll deduction formulas) ships its January edition.
• March through April: Provincial budgets are tabled. Most provincial tax brackets and credits are confirmed during this window. We refresh provincial data once each province's budget is formally passed.
• Every July: CRA T4127 ships its July edition, which typically includes mid-year payroll formula adjustments.
• Eight times a year (Bank of Canada decision dates): The overnight rate is updated within 24 hours of the announcement. Mortgage and other rate-sensitive calculators consume this value.
• As-needed: Tax rulings, federal budget announcements, and other off-schedule changes are applied within seven days of publication.

Reference test cases

Every calculator ships with a reference test suite: at least 10 cases for lower-risk tools (FHSA, TFSA, mortgage payment), at least 20 for high-risk tools (income tax, salary take-home, capital gains). Each case is a known scenario with a known expected output, drawn from CRA worked examples, provincial calculator outputs, or published CPA materials. The build fails if any test case diverges from the expected value by more than 1%. We will not promote a calculator from internal testing (noindex) to public indexing until its reference suite passes.

Correction service-level commitment

If you find an error in any calculator or piece of content on this site, we commit to:

• Acknowledgement within 24 hours of your email.
• Fix within 7 days of acknowledgement for clear formula or data errors.
• Public changelog entry describing what was wrong, what we changed, and when.

Report errors through the contact page.

Tool methodology pages

• First Home Savings Account (FHSA)

Additional tool methodology pages will be added as each calculator ships. Tools currently in development behind noindex will not appear here until they pass our gating criteria.