Self-test calculator
Type your numbers; see what the tool computes for a federal return. Nothing about your inputs leaves this browser tab.
What this is for
Robin built this to plug his own prepared-return numbers in and see if
the app reproduces the same federal refund. Same orchestrator
(computeFederalReturn) the API endpoint runs 292 audit
scenarios against. Same brackets, same QDCG worksheet, same credits
logic. If your number matches your prepared return, the math is
cross-verified for your shape.
What it covers
- Five filing statuses (Single / MFJ / MFS / HoH / QSS).
- Nine income source kinds — wages (W-2), self-employment, interest, ordinary + qualified dividends, short- and long-term capital gain, Sec 199A REIT dividends, foreign tax paid.
- Standard deduction (2025 inflation-adjusted), QBI on Sec 199A, QDCG worksheet for qualified-dividend + LT capital gain rates, Foreign Tax Credit direct path, Saver's Credit (Form 8880).
- Self-employment tax via Schedule SE (0.9235 × 0.153).
What's deferred
- State income tax — federal only this iter (iter-43+ adds state).
- Schedule A itemized deductions, Form 1116 over-threshold FTC, Child Tax Credit, EITC, education credits, K-1, rental, retirement distributions, Social Security, AMT.
- Multiple Saver's-Credit contributors on MFJ.
How to verify privacy
- Open DevTools → Network tab. Filter to "fetch / XHR". Clear.
- Type your numbers. Click Compute.
- The Network tab stays empty. No request fires.
- Refresh — the form blanks. Nothing persists.
The only way values leave this page is if you click Copy inputs as JSON, which writes to your local clipboard (user-initiated, OS-level — never a network call). That's deliberate: it lets you save your inputs to a local file if you want to come back to them.