How we verify 1099 Easy Guide
Every number on this site is checked by software before it reaches you. This page says exactly what is checked, against which documents, and when it last passed.
66 automated checks, last passed 4 August 2026
This site ships 2 acceptance suites totalling 66 assertions. They last passed in full on 4 August 2026. That date is not typed by anyone: it is written by the gate only when every check across all sites passes, and deleted the moment one fails, so this page cannot exist while the checks are red.
What each suite checks
- test_1099_tax_calc.py. 40 assertions. Acceptance tests for the full 1099 tax calculator. It runs the same JavaScript this site sends to your browser, not a copy of it.
- test_se_tax_calc.py. 26 assertions. Acceptance tests for the self-employment tax calculator. It runs the same JavaScript this site sends to your browser, not a copy of it.
Where these 8 figure families come from
Each figure carries two citations: the document that sets this year's amount, and the law that makes the figure exist at all. The second one does not change in January.
| Figure | This year's authority | Governing law |
|---|---|---|
| Additional Medicare tax | set by statute, not adjusted annually | IRC §3101(b)(2) (wages); IRC §1401(b)(2) (self-employment income) |
| Income tax brackets | Rev. Proc. 2025-32, retrieved 2026-08-01 | IRC §1(j) |
| Safe harbour | set by statute, not adjusted annually | IRC §6654(d)(1)(B) (90% / 100%); §6654(d)(1)(C) (110% above $150,000 AGI) |
| Quarterly due dates | Form 1040-ES (2026) instructions, retrieved 2026-08-02 | IRC §6654(c)(2) (installment due dates); IRC §7503 (weekend and legal-holiday shift) |
| FICA rates | set by statute, not adjusted annually | IRC §3101(a), §3101(b)(1) (employee); §3111(a), §3111(b) (employer) |
| Social Security wage base | SSA 2026 Cost-of-Living Adjustment announcement and Fact Sheet, retrieved 2026-08-02 | Social Security Act §230 (42 U.S.C. §430); incorporated by IRC §3121(a)(1) for wages and IRC §1402(b) for self-employment income |
| Qualified business income deduction | Rev. Proc. 2025-32, retrieved 2026-08-01 | IRC §199A |
| Self-employment tax | SSA 2026 COLA announcement (wage base component only), retrieved 2026-08-02 | IRC §1401(a) (12.4% OASDI), §1401(b) (2.9% HI); §1402(a)(12) (92.35% factor); §164(f) (deduction for half of SE tax) |
| Standard deduction | Rev. Proc. 2025-32, retrieved 2026-08-01 | IRC §63(c) |
| Payroll withholding | IRS Publication 15-T (2026), retrieved 2026-08-02 | IRC §3402 |
When we have got it wrong
A verification page that has never admitted an error is not evidence of anything.
On 1 August 2026 this portfolio found 4 live calculators computing 2025 tax on pages dated 2026, including a Social Security wage base of $176,100 where the same page said $184,500 five times. It was found by a gate that did not exist a day earlier, and it is why these checks now run against the shipping code rather than a copy of it. The full record is on our publisher's about page.
Where this comes from: SSA, 2026 COLA fact sheet (wage base set under 42 U.S.C. §430), checked 2026-08-01 · Social Security Act §230 (42 U.S.C. §430); incorporated by IRC §3121(a)(1) for wages and IRC §1402(b) for self-employment income.