PiggyQuarterly Estimated Tax Calculator 2026
Estimate your total federal tax for the year — self-employment plus income tax — and see exactly what to send the IRS each quarter. Educational planning; we don’t e-file.
This calculator uses 2026 tax figures. 2027 due dates are on the deadlines page; 2027 dollar limits are not fully published.
How this is calculated
Three taxes are combined and divided by four: self-employment tax (15.3% of 92.35% of profit), federal income tax using the 2026 brackets and standard deduction ($16,100 single / $32,200 joint), and your state rate. The qualified business income deduction is applied as the lesser of 20% of QBI and 20% of taxable income — the second limit is the one quick estimates usually miss.
Worked example: $30,000 of net profit with no state tax produces $4,239 of self-employment tax and $942 of federal income tax — $5,181 for the year, or $1,295 each quarter, an effective rate of 17.3%.
Same $73,000 example as the SE calculator (Q3 catch-up)
Figures match the published SE-tax worked examples (seTaxCalc + federalSetAside, simple QBI, 0% state, Single). Not a filed 1040-ES. Next IRS date on this site: September 15, 2026.
| What you look at | Annual | Equal quarterly (÷ 4) | If Q1 + Q2 were $0, catch-up by Q3 |
|---|---|---|---|
| SE tax only | $10,315 | $2,579 | $7,736 |
| SE + federal income tax, simple QBI, 0% state | $15,034 | $3,758 | $11,275 |
Load $73,000 / 0% state in this calculator (same query keys as the shareable URL on this page). PiggyMath does not e-file.
Your year
QBI mode note appears here after calculation.
Tax breakdown
2026 payment deadlines
| Quarter | Period covered | Due date |
|---|---|---|
| Q1 | Jan 1 – Mar 31 | Apr 15, 2026 |
| Q2 | Apr 1 – May 31 | Jun 15, 2026 |
| Q3 | Jun 1 – Aug 31 | Sep 15, 2026 |
| Q4 | Sep 1 – Dec 31 | Jan 15, 2027 |
All 2026–2027 dates: quarterly tax deadlines.
Never miss a deadline
Submit downloads a calendar file with a 3-day alert (and your on-screen estimate, on your device only). Email list uses double opt-in when connected — quarterly dates + rare tax-year updates only. Privacy.
For the full picture → Federal SE + income tax, state tax and full QBI on one screen — then come back here for deadlines.
How quarterly estimated taxes work
The U.S. tax system is pay-as-you-go. Employees have tax withheld from every paycheck; freelancers must instead send estimated payments four times a year using Form 1040-ES. This calculator combines your 2026 self-employment tax (15.3% on 92.35% of profit), federal income tax using the official 2026 brackets and standard deduction ($16,100 single / $32,200 married), the 20% qualified business income deduction, and your state's rate — then divides by four.
Two details this calculator gets right that quick estimates often miss. The QBI deduction is capped at 20% of your taxable income, not just 20% of profit, so at lower incomes it shrinks — ignoring that cap understates your bill by hundreds of dollars. Switch QBI detail level to Advanced to use the full §199A engine (SSTB phase-out, wage/UBIA limitation and the 2026 $201,750 / $403,500 thresholds) — the same math as the dedicated QBI calculator. And because every state defines its own deductions, the state figure applies your rate to profit after the self-employment tax adjustment, which errs slightly high: better to over-reserve than to be short in April.
To avoid an underpayment penalty, the IRS safe harbor is paying at least 90% of this year's tax or 100% of last year's (110% if your prior-year AGI topped $150,000). Every due date for both years is listed on our quarterly tax deadlines page, and the state-by-state guide shows which rate to enter above.
Frequently asked questions
What happens if I skip a quarterly payment?
How do I actually pay?
My income is unpredictable — what do I pay?
2026 figures are sourced in data/tax-constants-2026.json and listed with IRS/SSA links on Tax Constants 2026. Calculators read the mirrored values in assets/app.js (kept in sync by tools/verify_tax_constants.mjs). No Enrolled Agent or CPA has reviewed this page unless separately disclosed with credentials and a review date.
Sources
- IRS — Estimated Taxes (Form 1040-ES)
- IRS — Qualified Business Income Deduction (Section 199A)
- IRS — Self-Employment Tax (Social Security and Medicare Taxes)
- IRS Rev. Proc. 2025-32 — 2026 inflation adjustments
Every formula on this page is checked against an independent implementation before publication. How we check our math →