Who writes and checks this
Bedrock Calculator is an independent project built and maintained by one person. There is no separate editorial board and no credentialed reviewer, and this page will not claim one. An MBA in Marketing and Finance informs how calculators are scoped and explained; it is not a CPA, CFA, EA or attorney licence. Where a question needs a licensed professional, the site says so rather than answering it.
What stands in for a review board here is that the reasoning is written down and mechanically checked. A calculator is not published because someone believes it is right. It is published because its output matches reference values derived by hand from the source, and because a set of automated checks that can fail have all passed.
How the maths is verified
Every calculator ships with a test suite of reference values. Across the 1,094 published calculators there are currently 7,911 such tests in 1,324 files, and all of them must pass before anything is deployed.
The rule that makes those tests meaningful is that each expected value is derived independently, by working the formula or the statutory schedule by hand, with the arithmetic recorded in a comment beside the test. A value read back out of the function it is supposed to test proves only that the function is deterministic, not that it is correct, so that is not accepted as a test here.
Calculations run on exact decimal arithmetic rather than floating point, and the mathematics is documented separately on the methodology page.
Where statutory figures come from
Tax rates, brackets, thresholds, contribution limits and similar figures are taken from the government publication that issues them: the statute, the revenue authority's own document, or the national gazette. Figures are not copied from other calculator sites, aggregators or summaries, because a second-hand figure carries no way to tell when it was last correct.
Each stored figure records the document it came from and the date it was read. Every page lists its sources, and the count is shown next to the byline at the top so you can see at a glance whether a page rests on published sources or on standard mathematics that has no statutory origin. Pages of the second kind say so plainly rather than implying a source that does not exist.
When a source cannot be reached
Some government sites refuse automated access or publish only scanned documents. When a figure cannot be read from its primary source, it is not guessed and it is not taken from a secondary one. The most recent verified value is carried forward, marked in the code with the exact reason verification failed, and disclosed on the page that uses it.
There are currently 10 such disclosed figures across 7 of the international calculation modules. Four of those are deliberate tripwires that store no figure at all and require the reader to supply a current one. Two are not access problems: the rate genuinely varies by business category or region, so no single national number exists, and the calculator takes it as an input instead of inventing one.
A monitor re-checks those blocked sources weekly and reports when one becomes reachable, so a figure is revisited when there is a reason to rather than when someone remembers.
What runs before anything is published
Eight checks must pass on every change, and any one of them failing blocks the deployment:
- The full reference-value test suite.
- A type check across the whole codebase.
- Registry validation, which enforces the content depth floor and checks that each calculator's declared mathematics matches the code it actually calls, in both directions.
- An output-field audit, which catches a calculator that computes a schedule it never displays.
- A mechanism-claim check, which flags prose describing a step the code does not perform.
- A punctuation check, and a full production build.
A ninth check runs weekly rather than on every change, because it fails on the calendar rather than on a commit: it reports when the stored tax-year data falls behind the current year or when a figure has gone eighteen months without re-verification. 687 of the calculators here are sensitive to the tax year, so that check is deliberately designed to start failing on its own.
What these checks do not catch
The most useful thing a policy like this can say is where it is blind, so:
Automated checks confirm that the code does what the code says. They cannot confirm that a statutory figure is still current, only that it was verified on a recorded date. They compare a page's headline result against the engine, but not every intermediate figure in a worked example. And they cannot tell whether a simplification is reasonable for your situation, which is why each calculator has a section stating explicitly what it does not model.
The defect that has proved hardest to catch here is prose that describes a calculation more thorough than the one actually performed. It passes every numeric check, because the numbers are right; only the description is wrong. The mechanism-claim check above exists specifically for that failure, and it was made a blocking check only once it read clean, because a check that starts red teaches people to ignore it.
Corrections
When a figure is found to be wrong it is corrected at the source, the reference values are re-derived, and any wording on the page that repeated the old figure is updated in the same change. Where a page disclosed a limitation that no longer exists, the disclosure is removed, because a stale caveat misleads in the opposite direction.
If a calculation, a statutory rate or a citation looks wrong to you, that is the most useful thing you can send. Reach out through the contact page with the calculator name and what looks off, and it will be checked against the primary source directly.
Scope
Everything here is general-purpose calculation software. It is not personalised financial, tax or legal advice, and Bedrock Calculator is not a bank, financial institution, registered investment adviser, tax preparation firm or law firm. For a decision that matters, verify the result and speak to a licensed professional who knows your full situation. See the Terms of Service for the full disclaimer and the About page for who maintains this.