Editorial policy

Official sources only

A rate on UtilsKit means any official figure a calculation depends on: a tax rate, a contribution rate, a bracket, a cap or a published reference rate. Each one is taken from the body that sets or publishes it, such as a tax authority, a social insurance agency or a central bank, and is stored together with the address of that official page. Each country edition has a list of official domains, and an automated test fails when a figure points anywhere else. News articles, bank marketing pages and other calculators are not used as sources for a figure.

The sources behind a page are listed in its own sources section, linked directly to the agency's page or document, so you can check the figure yourself.

Effective year

Every figure is stored with the year it applies to, in the market's own reckoning: Taiwan pages use Republic of China years, for example 115 for 2026. A page that relies on yearly figures states which year it uses, so a calculation for one tax year is never silently presented as applying to another.

Last verified date

Each figure also carries the date on which it was last checked by opening the official source and reading the value there. The “Last updated” date at the foot of a calculator page is the latest of those dates for the figures it uses; a calculator that uses no official figure shows the date its content was last revised.

A figure that is missing its source, its year or its verification date is treated as unverified. Unverified figures are kept on a to-do list and cannot be shown as fact: the site will not build if a page tries to print one. Where a figure could not be confirmed, the page leaves it out rather than guessing.

How calculations are tested

Each calculator is one function that takes your inputs and the market's figures and returns the result, the schedule and the chart. The same function produces the result in the page source and recalculates it in your browser. Before a calculator is published, its function is tested against at least one worked example from an official body, such as the sample loan disclosure published by the US Consumer Financial Protection Bureau for the mortgage calculator, with the source of the expected figures written into the test.

How pages are updated

Figures change on the publisher's schedule, not on a fixed daily or weekly cycle. When an agency releases a new figure, for example Taiwan's central bank publishing the monthly average new mortgage rate of the five largest banks, or a tax authority publishing next year's brackets, the stored figure, its year and its verification date are updated together and the page's “Last updated” date moves with them. Until then a page shows the last figure that was verified and the date it was verified, so you can tell how current it is.

When an error is found, it is corrected in the same way: the figure is re-read from the source, the calculation tests are run again, and the date changes.

AI assistance

The text on UtilsKit pages, including the explanations, worked examples, scenarios and frequently asked questions, is drafted with the help of AI writing tools. AI output is never used as the source of a figure. Every official number is checked one by one against the agency's own page or document, and the numbers in worked examples come from the tested calculation function rather than being typed in by hand.

Advertising and independence

UtilsKit is funded by Google AdSense advertising on calculator and home pages. Advertisers have no say in the content, no one pays to be included in a result, and the pages do not tell you which product to buy. The calculators give arithmetic and general information, not personal financial, tax or legal advice. More about the publisher is on the About page.