People use our calculators to plan real decisions, so accuracy comes first. This page explains where our numbers come from, how we check them and how we keep them current.
Where our figures come from
We use official government sources wherever they exist: the IRS and state revenue departments in the US; the Canada Revenue Agency and Revenu Québec; HMRC, the Scottish and Welsh governments and the Student Loans Company in the UK; the Australian Taxation Office; the Revenue Commissioners in Ireland; and Inland Revenue and ACC in New Zealand. For each tax year we use the published rates, thresholds, payroll formulas and legislation. The sources behind every data set are listed on our methodology page and at the bottom of each guide.
When an official figure hasn't been published yet, for example a threshold that is indexed each year, we use the latest published figure or the official indexing rule, and say so in the calculator's assumptions.
How we check our work
- Every tax rule is entered once and shared by all the pages that use it, so a calculator, a salary page and a tax-rate table can never disagree.
- Before publishing changes, we recalculate sample cases by hand from the official rules and compare them with our results.
- We periodically review all our figures against official sources, looking for rule changes and anything we've missed.
Keeping things up to date
Tax rules change every year, and sometimes during the year. We update our calculators for each new tax year (January in the US, Canada and Ireland, April in the UK and New Zealand, July in Australia) and whenever a change is enacted mid-year. Each guide shows the date it was last reviewed. Upcoming budgets and changes are listed on our key dates page.
What our calculators include, and what they don't
Our calculators estimate the most common situations: employment income with standard deductions and allowances. Each one lists its assumptions and what it leaves out, such as other income, itemized deductions or less common credits. We never present an estimate as exact.
Corrections
If you find an error, email hello@financewithease.com. We check every report against the official source and fix confirmed errors as soon as we can.
Advertising and independence
FinanceWithEase is free and funded by advertising. Ads are shown in clearly separate spaces and never change our calculations, figures or guides. We don't accept payment to feature or rank financial products. If we ever add affiliate links, we'll label them clearly.
Not financial advice
Our calculators and guides are for general information and education. For decisions about your own situation, speak to a qualified professional. See our disclaimer.