Quarterly Tax Calculator
Estimate federal quarterly tax payments using projected annual self-employment income and expenses. Results run locally in your browser.
Estimate Your Quarterly Tax Payment
Estimated Results
This is an estimate for planning only. It does not include state taxes, credits, withholding adjustments, or safe-harbor planning nuances.
Why Your Quarterly Payment Feels Higher Than Expected
If you earn self-employment income — freelance work, 1099 contracts, consulting, or a side business — you probably owe quarterly estimated taxes. This calculator turns your projected annual income and expenses into a quarterly payment estimate so you know roughly how much to set aside before each IRS deadline.
The four deadlines for 2026 are April 15, June 15, September 15, and January 15, 2026. Miss one and you could face underpayment penalties — even if you're due a refund at year-end (IRS Publication 505).
This is a federal-only estimate. It doesn't include state taxes, penalty calculations, safe-harbor strategies, or prior-year withholding offsets.
How Self-Employment Tax Stacks on Top of Income Tax
Enter your expected annual income and business expenses, and the calculator runs a simplified federal tax projection:
- Projected profit = income minus expenses
- SE tax base = 92.35% of projected profit (IRC §1402(a)(12))
- Self-employment tax = Social Security + Medicare
- Social Security: 12.4% of the SE tax base, capped at $184,500
- Medicare: 2.9% of the SE tax base, no cap
- Adjusted income = profit minus half of SE tax (IRC §164(f))
- Taxable income = adjusted income minus standard deduction
- Federal income tax = progressive brackets on taxable income
- Quarterly payment = total estimated tax ÷ 4
The result is a single flat quarterly estimate. The IRS doesn't require equal payments — you can use the annualized income method (Form 2210, Schedule AI) to pay more in high-earning quarters and less in low ones. But this tool uses the equal-payment approach for simplicity (Form 1040-ES, Regular Method).
Example: $80,000 Income, $20,000 Expenses
Inputs: $80,000 self-employment income, $20,000 business expenses, single filer
| Step | Calculation | Amount |
|---|---|---|
| Projected profit | $80,000 − $20,000 | $60,000 |
| SE tax base (92.35%) | $60,000 × 92.35% | $55,410 |
| Social Security tax (12.4%) | $55,410 × 12.4% | $6,871 |
| Medicare tax (2.9%) | $55,410 × 2.9% | $1,607 |
| Total self-employment tax | $6,871 + $1,607 | $8,478 |
| 50% SE deduction | $8,478 ÷ 2 | −$4,239 |
| Adjusted income | $60,000 − $4,239 | $55,761 |
| Standard deduction (single, 2026) | −$16,100 | |
| Taxable income | $55,761 − $16,100 | $39,661 |
| Federal income tax | Progressive brackets | $4,511 |
| Total estimated tax | $8,478 + $4,511 | $12,989 |
| Quarterly payment | $12,989 ÷ 4 | $3,247 |
Due dates: April 15, June 15, September 15, January 15.
Step by Step: From Gross to Quarterly Payment
The calculation follows a simplified version of the Form 1040-ES estimated tax worksheet.
Income projection: Annual self-employment income minus annual business expenses equals projected profit.
Self-employment tax: The SE tax base is 92.35% of projected profit (IRC §1402(a)(12)). This adjustment roughly accounts for the employer-half deduction that W-2 employees don't pay. Social Security tax is 12.4% of that base, capped at $184,500 for 2026. Medicare tax is 2.9% of the base with no cap. Combined, the rate is 15.3% applied to the adjusted base rather than full profit (IRC §1401).
Income tax adjustment: Half of SE tax is deducted from profit before calculating income tax (IRC §164(f)). Adjusted income = profit − (SE tax ÷ 2).
Taxable income: Adjusted income minus the standard deduction. For 2026: $16,100 (single), $32,200 (married filing jointly), $24,150 (head of household).
Federal income tax: Progressive brackets applied to taxable income using 2026 rate thresholds for the selected filing status.
Quarterly division: Total estimated tax ÷ 4. Equal payments only. The annualized income method (Form 2210, Schedule AI) allows variable payments based on actual income each quarter, but this tool doesn't model that.
Assumptions:
- Income and expenses are projected for the full year, not entered per quarter
- All four payments are equal
- No tax credits applied
- No prior withholding or estimated payments subtracted
- No state or local tax included
- You expect to owe at least $1,000 in tax for the year (the IRS threshold that triggers the quarterly payment requirement, per IRC §6654)
Understanding Quarterly Estimated Taxes
Self-employed people don't have an employer withholding federal tax from each paycheck. Instead, the IRS expects tax to be paid during the year in installments.
2025 due dates:
| Period | Due date |
|---|---|
| January 1 – March 31 | April 15 |
| April 1 – May 31 | June 15 |
| June 1 – August 31 | September 15 |
| September 1 – December 31 | January 15, 2026 |
If a due date falls on a weekend or federal holiday, the deadline moves to the next business day.
Self-employment income creates two federal tax layers: income tax (based on taxable income after deductions) and self-employment tax (based on net earnings, covering Social Security and Medicare). This calculator combines both into a single quarterly estimate — a budgeting number, not a filing tool. If your income changes during the year, recalculate. The IRS doesn't penalize you for making up shortfalls in later quarters if you reach the safe-harbor threshold by year-end.
When You Might Owe More (or Less) Than the Estimate
- Freelancer setting aside tax after each client payment. You just got paid $5,000 for a project. If your annual profit projects to $60,000 and your quarterly estimate is ~$3,260, you know roughly how much of that payment should go to your tax reserve before the next deadline.
- Contractor whose income jumped mid-year. You projected $50,000 in January but now expect $80,000 by June. Run the calculator again with the updated estimate to see if Q3 and Q4 payments need to increase.
- First-time 1099 worker figuring out quarterly payments. The rule: if you expect to owe at least $1,000 in federal tax and have no withholding covering it, you generally need to make quarterly payments. This gives you a starting number.
- Side-business owner comparing expense assumptions. Run the calculator with and without a $5,000 equipment purchase to see how it changes the quarterly estimate — but this tool doesn't determine whether a specific expense is deductible under IRS rules.
FAQ
Does this include state tax?
No. Federal only. If you live in a state with income tax, your actual quarterly payments will be higher. California, New York, and other states have their own estimated tax requirements and due dates.
When are quarterly payments due?
April 15, June 15, September 15, and January 15 of the following year. Weekend or holiday deadlines move to the next business day (IRS Publication 505).
Why might my actual payment differ from this estimate?
Credits not modeled here, W-2 withholding that offsets the quarterly requirement, safe-harbor strategies based on prior-year tax, and the annualized income method for uneven earnings.
Does this use the IRS 92.35% self-employment tax adjustment?
Yes. SE tax is calculated on 92.35% of net earnings, not the full profit amount. This matches the IRS formula under IRC §1402(a)(12).
Does this account for the Social Security wage base cap?
Yes. The 12.4% Social Security portion stops at $184,500 in net earnings for 2026. Only the 2.9% Medicare portion applies above that.
Can I use quarterly income instead of annual?
Enter your best estimate of what the full year will total. If your income is uneven, recalculate when your projection changes.
What is the safe-harbor rule?
Pay at least 100% of your prior-year tax liability (110% if your AGI was over $150,000) and the IRS generally won't charge an underpayment penalty — even if your actual tax turns out higher. This tool doesn't evaluate safe-harbor status.
Data Sources
- Federal income tax brackets: IRS Revenue Procedure 2025-32, 2026 tax year
- Standard deduction: $16,100 / $32,200 / $24,150 — IRS, 2026
- Self-employment tax rate: IRC §1401 — 15.3% (12.4% Social Security + 2.9% Medicare)
- 92.35% SE adjustment: IRC §1402(a)(12)
- 50% SE tax deduction: IRC §164(f)
- Social Security wage base: $184,500 (2026) — SSA
- Quarterly payment structure and due dates: Form 1040-ES, IRS Publication 505
- Safe harbor thresholds: IRC §6654(d)(1) — 90% of current year tax or 100% of prior year tax (110% if AGI exceeded $150,000)
These are 2026 federal values and may change after tax law or inflation adjustments.
Limitations
No state or local taxes. Federal only. State income tax can add 5–13% on top — a significant gap for planning.
No penalty calculations. This tool doesn't calculate underpayment penalties (Form 2210). Miss a deadline or underpay, and the IRS charges interest on the shortfall.
No tax credits. Child Tax Credit, Earned Income Credit, education credits, and others that reduce your actual bill are not modeled.
No withholding offset. If you also have W-2 income with federal withholding, that withholding reduces your required quarterly payments. Not accounted for here.
No safe-harbor planning. The safe-harbor rule (pay 100% of prior-year tax, or 110% if AGI was over $150,000) can protect you from penalties even if estimates are wrong. Not evaluated here.
Equal quarterly payments only. Annual tax ÷ 4. The IRS allows the annualized income method (Form 2210 Schedule AI) for variable income quarters.
No QBI deduction. The Qualified Business Income deduction (Section 199A) can reduce taxable income by up to 20% of qualified business income. Not modeled.
Not tax advice. This is a planning estimate. Consult a tax professional or use IRS Form 1040-ES directly for filing decisions.