How we verify rates and test spreadsheets

Sources

We use official sources only for fees and rates: the platform's own fee policy or pricing page, and irs.gov for tax figures. Every number on the site comes from one registry file, with its source URL, the date we last verified it and the date of its next check.

Schedule

Platform fees are re-checked weekly and IRS rates monthly. When a source changes, we update the registry, the tools and the matching spreadsheets, and log the change on the fee change tracker.

Testing

Spreadsheet formulas are checked against hand-calculated expected values and recalculated in a second spreadsheet app before release. Calculators show their working so you can check them.

Review

Content is written with AI assistance and edited by Plain Sheet Co. It has not yet been reviewed by a CPA or Enrolled Agent; we will say so on each page when that changes.

Corrections

If you spot an error, tell us and we will fix it and note the change on the tracker.