Self Assessment Tax Calculator 2026
Calculate Your Self-Employed Taxes & Quarterly Payments for Tax Year 2026
Based on official IRS Self-Employment Tax Center
Enter Your Self-Employment Income Information
2026 Self Assessment Tax Calculation
📅 2026 Quarterly Estimated Tax Payments
How to Complete Self Assessment Tax Calculation
- Track All Income: Gather 1099-NEC, 1099-K, and other income forms from clients and platforms.
- Calculate Net Profit: Subtract allowable business expenses from gross income.
- Compute Self-Employment Tax: Apply 15.3% rate to 92.35% of net self-employment earnings.
- Take Adjustments: Deduct 50% of SE tax, health insurance, and retirement contributions.
- Apply QBI Deduction: Take 20% Qualified Business Income deduction if eligible.
- Calculate Federal Tax: Apply 2026 tax brackets to taxable income.
- Determine Quarterly Payments: Divide annual tax by 4 for quarterly estimated payments.
- File and Pay: Submit Form 1040 with Schedule C and SE; pay via IRS Direct Pay or EFTPS.
Self Assessment Tax Formulas for 2026
Net Self-Employment Income
Self-Employment Tax Calculation
Qualified Business Income Deduction
Total Tax Liability
Quarterly Estimated Payment
2026 Federal Tax Brackets
| Tax Rate | Single | Married Filing Jointly | Head of Household |
|---|---|---|---|
| 10% | $0 - $11,925 | $0 - $23,850 | $0 - $17,000 |
| 12% | $11,926 - $48,475 | $23,851 - $96,950 | $17,001 - $64,850 |
| 22% | $48,476 - $103,350 | $96,951 - $206,700 | $64,851 - $103,350 |
| 24% | $103,351 - $197,300 | $206,701 - $394,600 | $103,351 - $197,300 |
| 32% | $197,301 - $250,525 | $394,601 - $501,050 | $197,301 - $250,500 |
| 35% | $250,526 - $626,350 | $501,051 - $751,600 | $250,501 - $626,350 |
| 37% | Over $626,350 | Over $751,600 | Over $626,350 |
2026 Standard Deductions & Key Limits
| Item | 2026 Amount |
|---|---|
| Standard Deduction (Single) | $15,000 |
| Standard Deduction (MFJ) | $30,000 |
| Standard Deduction (HOH) | $22,500 |
| Social Security Wage Base | $174,900 |
| Standard Mileage Rate | 70 cents/mile (est.) |
| SEP-IRA Limit | $70,000 |
| Solo 401(k) Limit | $23,500 + employer |
2026 Quarterly Payment Due Dates
| Quarter | Income Period | Due Date |
|---|---|---|
| Q1 | January 1 - March 31, 2026 | April 15, 2026 |
| Q2 | April 1 - May 31, 2026 | June 15, 2026 |
| Q3 | June 1 - August 31, 2026 | September 15, 2026 |
| Q4 | September 1 - December 31, 2026 | January 15, 2027 |
Official IRS Resources
Tax Forms
Schedule C - Profit or LossSchedule SE - Self-Employment Tax
Form 1040-ES - Estimated Tax
Frequently Asked Questions
Self assessment tax is the process where self-employed individuals, freelancers, and independent contractors calculate and pay their own taxes. Unlike W-2 employees whose taxes are withheld, self-employed workers must estimate and pay taxes quarterly, including both income tax and self-employment tax (Social Security + Medicare).
Self-employment tax is 15.3% of net self-employment earnings: 12.4% for Social Security (up to $174,900 wage base in 2026) and 2.9% for Medicare (no cap). An additional 0.9% Medicare surtax applies to income over $200,000 (single) or $250,000 (MFJ). The tax is calculated on 92.35% of net earnings.
For 2026, quarterly payments are due: Q1 - April 15, 2026; Q2 - June 15, 2026; Q3 - September 15, 2026; Q4 - January 15, 2027. Pay via IRS Direct Pay or EFTPS.
Common deductions include: home office ($5/sq ft simplified), vehicle (70¢/mile est. for 2026), equipment, supplies, software, advertising, professional services, insurance, phone/internet, travel, meals (50%), continuing education, and retirement contributions (SEP-IRA, Solo 401(k)).
The Section 199A Qualified Business Income deduction allows self-employed individuals to deduct up to 20% of their net business income. Phase-outs apply for specified service businesses (consulting, health, law, accounting) when taxable income exceeds thresholds (~$191,950 single / ~$383,900 MFJ for 2026).
Yes, if you expect to owe $1,000+ in taxes after subtracting withholding and credits. To avoid penalties, pay either 100% of prior year's tax liability or 90% of current year's tax in quarterly installments. High earners ($150K+ AGI) must pay 110% of prior year tax.
Gig workers (Uber, DoorDash, Instacart, etc.) file Schedule C with Form 1040. You'll receive 1099-K or 1099-NEC forms. Track all income and deductible expenses (mileage, phone, supplies). Make quarterly estimated payments and pay SE tax on net earnings.
Yes, self-employed individuals can deduct 100% of health insurance premiums for themselves, spouse, and dependents as an above-the-line deduction. This reduces both income tax and the base for calculating QBI deduction. The deduction cannot exceed your net self-employment income.
SEP-IRA: up to 25% of net SE income (max $70,000 for 2026). Solo 401(k): $23,500 employee + 25% employer contribution. SIMPLE IRA: $16,500 + match. Contributions reduce taxable income and grow tax-deferred. Deadline to establish: year-end (401k) or tax filing date (SEP).
The underpayment penalty is calculated at the federal short-term rate plus 3% (compounded daily). For 2026, expect ~8% annually. Penalty applies to each quarter's underpayment from due date until paid. Avoid by paying 100% of prior year tax or 90% of current year tax.
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Last Updated: January 2025 | Projected Tax Year 2026 Rates
