1099Local

Methodology & sources

A tax calculator is only as trustworthy as its numbers and its honesty about what it skips. This page is both, in full: every 2026 figure the estimator uses, where it came from, and the list of things it deliberately does not model. All figures compiled 18 July 2026 from the sources cited; this page and the calculator render from the same single data file, so they cannot disagree with each other. Found an error? Tell us — corrections outrank all other mail.

How the estimate is computed

The engine follows the Form 1040-ES worksheet’s structure: net profit (income − expenses) → self-employment tax via Schedule SE (92.35% factor; 12.4% Social Security to the wage base, 2.9% Medicare throughout; no SE tax under $400 of net earnings) → AGI including the deduction for half of SE tax → standard or user-supplied itemized deduction → QBI deduction → the 2026 brackets → Child Tax Credit → plus Additional Medicare Tax — then W-2 withholding is subtracted and the remainder is spread across the IRS deadlines. W-2 wages reduce the Social Security wage base available to self-employment earnings before the 12.4% is applied, and reduce the Additional-Medicare threshold per the Form 8959 ordering.

2026 federal income-tax brackets

Source: IRS Rev. Proc. 2025-32 (October 2025, as amended by the One Big Beautiful Bill Act), cross-checked against the IRS newsroom release and Tax Foundation’s 2026 tables.

Rate SingleMarried filing jointlyMarried filing separatelyHead of household
10% $0 – $12,400 $0 – $24,800 $0 – $12,400 $0 – $17,700
12% $12,400 – $50,400 $24,800 – $100,800 $12,400 – $50,400 $17,700 – $67,450
22% $50,400 – $105,700 $100,800 – $211,400 $50,400 – $105,700 $67,450 – $105,700
24% $105,700 – $201,775 $211,400 – $403,550 $105,700 – $201,775 $105,700 – $201,775
32% $201,775 – $256,225 $403,550 – $512,450 $201,775 – $256,225 $201,775 – $256,200
35% $256,225 – $640,600 $512,450 – $768,700 $256,225 – $384,350 $256,200 – $640,600
37% $640,600 – ∞ $768,700 – ∞ $384,350 – ∞ $640,600 – ∞

Deductions, credits and payroll-tax parameters

Parameter2026 valueSource
Standard deduction $16,100 single / $32,200 joint / $16,100 separate / $24,150 head of household IRS Rev. Proc. 2025-32
Social Security wage base $184,500 SSA contribution & benefit base announcement
SE tax structure 12.4% + 2.9% on 92.35% of net profit; $400 floor; half deductible IRS Schedule SE / Form 1040-ES
Additional Medicare Tax 0.9% over $200,000 single & HoH / $250,000 joint / $125,000 separate IRS Topic 560 / Form 8959
QBI deduction (§199A) 20% of QBI, capped at 20% of taxable income; thresholds $201,775 single / $403,500 joint; $400 minimum at ≥$1,000 QBI OBBBA (permanent); Tax Foundation 2026 figures; Warren Averett / RSM on the minimum
Child Tax Credit $2,200 per child under 17; −$50 per $1,000 of AGI over $200,000 ($400,000 joint) IRS; OBBBA
Safe harbor Lesser of 90% current-year or 100% prior-year tax (110% over $150,000 prior AGI; $75,000 MFS); no estimates under $1,000 owed IRS Form 1040-ES / estimated-tax FAQ
2026 deadlines 2026-04-15 · 2026-06-15 · 2026-09-15 · 2027-01-15 IRS 2026 Form 1040-ES calendar

What the estimator deliberately does not model

Net effect: for a typical self-employed filer using the standard deduction, the estimate tracks the 1040-ES worksheet closely; for filers with the unmodelled items above, it tends to overstate tax — the safe direction for a payment planner. It remains an estimate for planning, not advice for your situation.

Annual refresh

Tax tables are refreshed when the IRS publishes each year’s inflation adjustments (typically October–November) and the SSA announces the wage base. The tax year in force on every page of this site is stated in the calculator itself — currently 2026. If you’re reading this long after a January and the year above looks stale, say so.