How is Self-Employment (SE) tax calculated for a sole proprietor or single-member LLC?

The IRS applies Self-Employment tax to 92.35% of your net Schedule C business profit (Gross Revenue minus allowable business expenses). That amount is taxed at 12.4% for Social Security (up to the annual wage base cap) plus 2.9% for Medicare—totaling 15.3%. Half of your SE tax is then deducted from your Adjusted Gross Income before calculating federal income tax.

How much of each paid client invoice should a small business owner set aside for taxes?

Most profitable U.S. contractors and 1099 operators set aside 22% to 30% of their Net Profit (or roughly 15% to 25% of Gross Revenue depending on material costs and state income tax) into a separate tax savings account every Friday so quarterly IRS deadlines never hurt cash flow.

When are IRS Form 1040-ES quarterly estimated taxes due?

IRS quarterly estimated tax payments are due four times per year: April 15 (Q1: Jan–Mar), June 15 (Q2: Apr–May), September 15 (Q3: Jun–Aug), and January 15 of the following year (Q4: Sep–Dec). If a due date falls on a weekend or federal holiday, it shifts to the next business day.

What is the 20% Qualified Business Income (QBI) deduction?

Under Section 199A, eligible U.S. pass-through small businesses (sole proprietors, single-member LLCs, partnerships, and S-Corps) can generally deduct up to 20% of their qualified net business income from federal taxable income—lowering federal income tax without costing a dollar out of pocket.

Can I deduct work truck or car mileage on Schedule C?

Yes. You can deduct business miles driven between job sites, client meetings, and supply houses using either the IRS standard mileage rate ($0.70/mile) or actual vehicle expenses—just keep a contemporaneous mileage log and note that commuting from home to a permanent office is not deductible.

Small Business & 1099 Quarterly Tax Calculator (2026)

Small Business & 1099 Quarterly Tax Calculator

Know exactly what is safe to spend and what to set aside for the IRS—without double-entry accounting jargon. Built for U.S. contractors, LLCs, and solo pros.

Sample Profiles:

Important Disclaimer — Not Tax or Legal Advice: We are software builders, not tax lawyers, CPAs, or enrolled agents. These numbers are simplified 2026 planning estimates—always verify your final deductions, state/local rules, and quarterly payments with a licensed professional accountant or CPA before filing or paying taxes.

1. Filing Status & State

U.S. State

State Tax Rate (%)

2. Annual Money In (Gross Receipts)

Annual Business / 1099 Gross Revenue ($)

Total paid invoices, cash/check jobs & 1099-NEC / 1099-K receipts.

Optional W-2 Day-Job Salary ($)

Adjusts tax bracket & $184,500 Social Security wage cap automatically.

3. Business Expenses & Work Mileage (Schedule C)

Every $1,000 in legitimate business write-offs saves ~$215 in taxes.

Materials, Parts & Job Supplies ($)

Contract Labor / Subcontractors ($)

Tools, Equipment & Repairs ($)

Business Insurance, Bonds & Licenses ($)

Advertising, Website & Local SEO ($)

Software, Phone & Office Supplies ($)

Business Miles Driven ($0.70/mile IRS Standard Rate)

Adds $8,050 vehicle write-off automatically.

miles/yr

Apply 20% QBI Deduction (Sec. 199A) Saves $2,929–$3,195 for eligible pass-through LLCs & sole props.

SEP-IRA / Solo 401(k) + Health Ins. ($)

Safe-to-Spend Take-Home

$69,849/yr

≈ $5,821/month after expenses & taxes

Set Aside Per Job

14.1%

of gross invoices

Keep: 52% Taxes: 14% (21.5% of profit) Write-Offs: 34%

Quarterly IRS 1040-ES Payment

$4,775/qtr

Q1 • Apr 15

$4,775

Q2 • Jun 15

$4,775

Q3 • Sep 15

$4,775

Q4 • Jan 15

$4,775

Next Due

CPA-Ready Schedule C Summary

Gross Business Revenue $135,000

Cash Expenses + Mileage (11,500 mi) -$46,050

Net Schedule C Profit $88,950

Self-Employment Tax (SS + Medicare) $12,568

Federal Income Tax (after 20% QBI) $6,533

State Income Tax (TX @ 0%) $0

Total Annual Estimated Tax $19,101

Not a Tax Lawyer or CPA: For rough planning only. Always review your final numbers with a qualified accountant or CPA before submitting IRS/state tax payments.

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