Contact
Found a bug, spotted a wrong number, or want a tool that does not exist yet? We genuinely want to hear it: error reports get fixed fast, and reader suggestions decide which tools get built next.
Write to hello at hopi dot co dot uk and a human will read it. If you are reporting a wrong result, include the tool, the numbers you entered and the answer you expected, and we can usually sort it the same week.
What we cannot help with
We cannot give personal financial, tax or legal advice, so please do not send details of your personal situation. For tax questions, gov.uk is the authoritative source.