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How we calculate
This page lists every number and formula our calculators use, where each number comes from, and what the calculators deliberately leave out. Last reviewed October 11, 2026, for tax year 2026.
Order of operations
- Net profit (Schedule C): gross gig earnings − (Jan–Jun miles × 72.5¢) − (Jul–Dec miles × 76¢) − other business expenses.
- Self-employment tax (Schedule SE): net profit × 92.35% = SE earnings. If SE earnings are under $400, SE tax is $0. Social Security = 12.4% × the lesser of SE earnings and ($184,500 − W-2 wages). Medicare = 2.9% × SE earnings. Additional Medicare = 0.9% on combined wages and SE earnings above $200,000 (single/HOH), $250,000 (joint), or $125,000 (separate).
- Adjusted gross income: W-2 wages + net profit − ½ of (Social Security + Medicare portions of SE tax).
- Standard deduction for the filing status, plus the additional amount for each person age 65+.
- Tips deduction (Schedule 1-A): the lesser of qualified tips, $25,000, and net profit; reduced by $100 for each full $1,000 of modified AGI above $150,000 ($300,000 joint). Zero if married filing separately or without a work-valid SSN.
- Senior deduction: $6,000 per person 65+, reduced by 6% of modified AGI above $75,000 ($150,000 joint). Same SSN and filing-status rules as the tips deduction.
- QBI deduction (Section 199A): 20% × (net profit − ½ SE tax), limited to 20% of taxable income before this deduction. Above the threshold ($201,750 single, $403,500 joint) it phases to zero over $75,000 ($150,000 joint), because a solo driver pays no W-2 wages. With at least $1,000 of QBI, a $400 minimum applies (we cap it at taxable income).
- Federal income tax: taxable income through the 2026 brackets below.
- State tax (estimate): an approximate effective rate × AGI. See limits below.
- Set-aside %: (total tax − tax you would owe on your W-2 job alone) ÷ gross gig earnings.
2026 federal tax brackets
Single (standard deduction $16,100; +$2,050 per person 65+)| Rate | Taxable income up to |
|---|
| 10% | $12,400 |
| 12% | $50,400 |
| 22% | $105,700 |
| 24% | $201,775 |
| 32% | $256,225 |
| 35% | $640,600 |
| 37% | and above |
Married filing jointly (standard deduction $32,200; +$1,650 per person 65+)| Rate | Taxable income up to |
|---|
| 10% | $24,800 |
| 12% | $100,800 |
| 22% | $211,400 |
| 24% | $403,550 |
| 32% | $512,450 |
| 35% | $768,700 |
| 37% | and above |
Married filing separately (standard deduction $16,100; +$1,650 per person 65+)| Rate | Taxable income up to |
|---|
| 10% | $12,400 |
| 12% | $50,400 |
| 22% | $105,700 |
| 24% | $201,775 |
| 32% | $256,225 |
| 35% | $384,350 |
| 37% | and above |
Head of household (standard deduction $24,150; +$2,050 per person 65+)| Rate | Taxable income up to |
|---|
| 10% | $17,700 |
| 12% | $67,450 |
| 22% | $105,700 |
| 24% | $201,750 |
| 32% | $256,200 |
| 35% | $640,600 |
| 37% | and above |
2026 estimated tax due dates
| Payment | Income earned | Due |
|---|
| Q1 | Jan 1 – Mar 31, 2026 | April 15, 2026 |
| Q2 | Apr 1 – May 31, 2026 | June 15, 2026 |
| Q3 | Jun 1 – Aug 31, 2026 | September 15, 2026 |
| Q4 | Sep 1 – Dec 31, 2026 | January 15, 2027 |
What the calculators leave out
- Credits: Child Tax Credit, Earned Income Tax Credit, education credits, and the Premium Tax Credit are not included. If you qualify for any of these, your actual bill will be lower.
- Other deductions: self-employed health insurance, retirement contributions, student loan interest, and itemized deductions are not modeled yet.
- State and local tax: the state line uses one approximate effective rate per state, chosen for a typical full-time gig income. It does not apply each state's brackets, credits, or local income taxes (for example New York City or many Ohio and Pennsylvania cities). You can type your own rate.
- Actual-expense vehicle method: we use the standard mileage rate, which most drivers choose.
- Losses: a net loss lowers AGI but never creates negative SE tax.
Sources
- IRS Rev. Proc. 2025-32 — 2026 brackets, standard deduction, and other inflation adjustments
- IRS news release IR-2025 (December 2025) — 72.5¢ business mileage for 2026; IRS Announcement 2026-11 — 76¢ for miles driven on or after July 1, 2026
- Social Security Administration — 2026 contribution and benefit base ($184,500)
- IRS — What the "No Tax on Tips" deduction means for you; Treasury final regulations on qualified tips (2026)
- IRS — Schedule SE instructions; Form 8995 instructions (QBI); Form 1040-ES (estimated tax)
- Public Law 119-21 ("One Big Beautiful Bill Act") — tips deduction, senior deduction, QBI minimum deduction, 1099-NEC threshold
Testing
The calculation engine is covered by automated tests that check bracket math, the Social Security wage base, the $400 SE threshold, the tips deduction caps and phase-out, and complete worked examples computed by hand. Every change to a tax figure must pass these tests before it goes live.
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