How we check returns
Last updated November 12, 2026
This is how we check TideTax, and what those checks don't cover.
Checked against independent calculations
We calculate thousands of test returns with TideTax and with independent tax calculators, federal and California, and compare the results. In our latest run, on November 12, 2026, none disagreed.
Checked against professionally prepared returns
We run real documents through TideTax and compare the result line by line with the return that was actually filed, prepared by a CPA or with commercial tax software. The lines match, apart from a few differences we've traced and can explain.
Finished forms are checked too
In testing, the values printed on the finished forms are checked against our calculation, the forms' own arithmetic and each other.
We block what we don't support
If your return needs something we don't handle, we stop and tell you instead of guessing. Today that includes K-1s, self-employment, rental income, foreign tax over $300, and part-year residency or another state's income tax.
When we read your documents, we check them too. If a number breaks its own form's math, we ask you to look at it before it goes on your return.
What to know
- These are our own tests. No outside firm or government agency has reviewed them.
- Test returns check the math, not how we read your documents. You review what we read.
No test can promise your return is right. Review it before you sign: what you file is your responsibility.