Contact
Found a mistake, or want a calculator that is not here yet? We read everything.
Write to hello@knownsum.com. We aim to reply within 2 business days.
What to contact us about
- A result that looks wrong, or a tax figure, rate or fee that looks out of date.
- A question about how a calculator works or where one of its figures comes from.
- A calculator or a state you would like us to add.
- Anything on the site that is broken or hard to use on your device.
Reporting a calculation error
Every figure on KnownSum comes from the IRS, a state agency or the law itself, and each calculator page lists its sources and the date its figures were last verified. If you think a result is wrong, please include:
- The address of the page, and the figures you entered.
- What you expected to see, and where you found the rule or figure you are comparing against.
We check the report against the official source, correct the page if needed, and update its last-verified date. You can see how each calculation is worked in our methodology, and every official document we rely on in our sources.
What we cannot do
We cannot give tax advice or look at your personal return. For that, speak to a qualified tax professional. Please do not send Social Security numbers or other sensitive documents.