Why this page exists
Money advice affects real lives, so you should be able to see how we get our numbers. This page explains how we work.
Where our figures come from
We use primary sources first: the tax authority, the pension body or the law itself. For the United States that means sources such as the IRS and the Social Security Administration. Every calculator and guide lists its sources, and we link to them.
We aim not to publish a limit, rate or table that we cannot trace to an official source. If a source is unclear, we say so on the page.
How we build a calculator
- We write down the formula and the source of every number.
- We build the calculation as a small, separate piece of code.
- We test it against hand-worked examples and against edge cases such as zero, very large numbers and impossible ages.
- We read the result as a reader would, and rewrite anything that is confusing.
- We publish the date we last checked the figures.
How often we review
Limits and rates are reviewed at least once a year, and again when an official body announces a change. Each page shows when it was last reviewed.
Corrections
If you find an error, tell us through the contact page. We check it against the source, fix confirmed errors quickly, and update the "last reviewed" date. If a mistake could have affected a decision, we note the correction on the page.
Tools and drafting
We use software tools, including AI-assisted tools, to help draft text and write and test code. Software does not decide what is true. We check figures against an official source before they are published, and we re-check them at least once a year.
Advertising and independence
Advertising and partner links never decide what we write, which calculators we build, or what a result says. Ads are labelled and kept apart from results. See our advertising and affiliate disclosure.
What we are not
We are not a bank, broker, tax adviser or financial planner. Our calculators are estimates for learning and planning. Please read our disclaimer.