Self-Employment Tax Calculator 2026 — 1099 Tax and Quarterly Estimates
On $120,000 of 1099 income with $15,000 of expenses, you owe about $28,719 in total tax — $14,836 of self-employment tax plus federal and state income tax, an effective rate of 23.9% on gross revenue. Self-employment tax is 15.3% charged on 92.35% of net business income, and it applies before any income tax deduction. Paid quarterly, that is about $4,500 per payment on the four dates below.
| 1099 / business income | $120,000.00 |
|---|---|
| Business expenses | −$15,000.00 |
| Self-employment tax — Social Security (12.4%) | −$12,023.97 |
| Self-employment tax — Medicare (2.9%) | −$2,812.06 |
| Federal income tax | −$9,052.83 |
| California income tax | −$4,830.10 |
| Net business incomeGross revenue minus deductible business expenses. This is what SE tax is calculated on. | $105000.00 |
| SE tax base (92.35%)SE tax is calculated on 92.35% of net self-employment earnings — the 7.65% adjustment mirrors the employer-side FICA that a W-2 worker's employer pays. Half of the resulting SE tax is deductible from AGI as an above-the-line deduction. | $96967.50 |
| Deductible half of SE taxReduces your income tax, not your SE tax. | $7418.02 |
| QBI deductionSection 199A deduction of 20% of qualified business income. | $16296.40 |
| Federal marginal rate | 22% |
| Total tax owed | $28718.96 |
| Total tax owed | $76,281.04 |
A solo 401(k) would let you contribute roughly $21,000 at this income level, cutting your federal income tax by about $4,620.
Your quarterly payment schedule
Paying 100% of last year's $18,000 tax bill is the cheaper safe harbour. Pay $18,000 across the year and no underpayment penalty applies, even if you end up owing more.
| Quarter | Income period | Payment due | Amount |
|---|---|---|---|
| Q1 | 1 Jan – 31 Mar | Apr 15, 2026 | $4,500.00 |
| Q2 | 1 Apr – 31 May | Jun 15, 2026 | $4,500.00 |
| Q3 | 1 Jun – 31 Aug | Sep 15, 2026 | $4,500.00 |
| Q4 | 1 Sep – 31 Dec | Jan 15, 2027 | $4,500.00 |
| Total for the year | $18,000.00 | ||
How the tax is worked out
Three separate taxes on the same income, calculated in an order that matters, because each one's base is different from the last.
Self-employment tax comes first and is barely reducible: only business expenses shrink its base. Retirement contributions, health insurance, and the standard deduction all reduce income tax and leave self-employment tax untouched. That is why a high earner's marginal rate on the next 1099 dollar is so much higher than the bracket table suggests.
The retirement contribution trap
Here is a claim you will find on every other 1099 tax page: a solo 401(k) contribution is deductible at your marginal rate, so at 22% a $10,000 contribution saves you $2,200. It does not, if you also claim the QBI deduction — and almost every sole proprietor does.
Qualified business income under Section 199A is computed after subtracting your retirement contribution. So the contribution does two things at once: it removes $10,000 from taxable income, and it removes $10,000 from the base of a deduction worth 20% of that base. You give back $2,000 of QBI deduction to get $10,000 of deduction.
| $10,000 into a solo 401(k) | Federal tax saved | Effective rate |
|---|---|---|
| What 22% marginal implies | $2,200 | 22.00% |
| What you actually save, claiming QBI | $1,760 | 17.60% |
| Same contribution, QBI not claimed | $2,200 | 22.00% |
The third row is the proof rather than a footnote: switch the QBI deduction off and the same contribution saves the full marginal rate again. The gap is the clawback, and it is exactly 22% × 0.8 = 17.60%.
State tax pulls in the opposite direction. Most states, California included, do not conform to Section 199A — there is no QBI deduction to claw back, so the contribution deducts in full at state rates. Including California, the same $10,000 saves $2,690 rather than $1,760. The total is genuinely two different calculations stacked, which is why a single "marginal rate" figure cannot answer this.
The quarters are not quarters
Estimated tax is due four times a year on periods that are not three months long and do not line up with calendar quarters:
| Quarter | Income period | Months | Payment due |
|---|---|---|---|
| Q1 | 1 Jan – 31 Mar | 3 | April 15, 2026 |
| Q2 | 1 Apr – 31 May | 2 | June 15, 2026 |
| Q3 | 1 Jun – 31 Aug | 3 | September 15, 2026 |
| Q4 | 1 Sep – 31 Dec | 4 | January 15, 2027 |
Q2 is two months. Q4 is four, and its payment falls in January of the following year — after the tax year has closed. If you pay equal instalments against an annual estimate none of this matters. It matters a great deal if your income is lumpy and you annualise each period, because the IRS assesses what you earned inside each period rather than what a calendar quarter would suggest.
A worked example
$120,000 of 1099 income, $15,000 of expenses, California
| Line | Working | Amount |
|---|---|---|
| 1099 income | gross | $120,000 |
| Business expenses | deductible | −$15,000 |
| Net business income | SE tax is charged on this | $105,000 |
| Self-employment tax | 15.3% × 92.35% | −$14,836.03 |
| QBI deduction | Section 199A | $16,296 off taxable income |
| Federal income tax | after ½ SE tax and QBI | −$9,052.83 |
| California income tax | no QBI conformity | −$4,830.10 |
| Total tax | 23.9% of gross revenue | −$28,718.96 |
| Yours to keep | after expenses and tax | $76,281.04 |
Self-employment tax alone is $14,836.03 — more than the federal income tax bill of $9,052.83 at this income level. That inversion surprises people who budget by thinking about their tax bracket, and it is why the first profitable 1099 year so often ends with a bill nobody set money aside for.
Who this is for
Anyone with 1099 income who has to send the IRS money four times a year, and anyone in their first profitable year of self-employment trying to work out how much to hold back. Enter last year's tax and AGI if you have them — the prior-year safe harbour is frequently a much lower target than 90% of this year's bill, and knowing that is worth real cash flow.
What this does not account for
- S-corp election. Everything here models a sole proprietor filing Schedule C.
- Annualised income instalments (Form 2210 Schedule AI), which can reduce penalties when income genuinely arrived late in the year.
- Credits beyond the standard/itemized deduction and QBI — child tax credit, education credits, and the premium tax credit all change the final number.
- Local income tax in cities that levy one.
- 5 states are modelled (California, Florida, Illinois, New York, Texas). Others run federal only.
- This is an estimate, not advice. It is arithmetic on published IRS parameters. A CPA is worth their fee at this income level.
Sources and dates
Federal brackets, the FICA wage base, self-employment tax rates, QBI thresholds, estimated-tax due dates, and state schedules come from the IRS and state revenue departments for tax year 2026, listed below with the date each was checked. The QBI clawback figures are computed by running this page's own engine with the deduction on and off — not quoted from anywhere. If a figure disagrees with your accountant, trust your accountant and let us know.
Questions people actually ask about this
How much self-employment tax will I owe on 1099 income?
15.3% of 92.35% of your net business income — an effective 14.13% — split as 12.4% Social Security and 2.9% Medicare. On $120,000 of revenue less $15,000 of expenses, that is $14,836.03.
That is before any income tax. The 92.35% adjustment exists because an employee's employer pays half of FICA out of pre-tax money, and this mirrors it. Half of the resulting SE tax is then deductible from your AGI — which reduces income tax, not the SE tax itself.
Is a solo 401(k) contribution really deductible at my marginal rate?
Not federally, if you also claim the QBI deduction — and this is the most expensive misconception in 1099 tax planning. Qualified business income is computed after your retirement contribution, so every dollar you contribute also shrinks the 20% QBI deduction by twenty cents. The federal benefit is your marginal rate times 0.8.
Proved on this page's inputs: a $10,000 contribution saves $1,760 in federal tax, not the $2,200 that 22% of $10,000 implies. The QBI deduction falls by $2,000 — exactly 20% of the contribution. Turn QBI off in the calculator and the same contribution saves $2,200, the full marginal rate, which confirms the clawback is what causes the gap.
It is still worth contributing. It is just worth knowing the real rate is 17.60% federally rather than 22%, because that changes where the contribution ranks against paying down debt or simply taking the money.
Do the quarterly deadlines cover equal quarters?
No, and this catches people every year. The four periods are:
- Q1 — income from 1 Jan – 31 Mar, due April 15, 2026
- Q2 — income from 1 Apr – 31 May, due June 15, 2026
- Q3 — income from 1 Jun – 31 Aug, due September 15, 2026
- Q4 — income from 1 Sep – 31 Dec, due January 15, 2027
Q2 covers two months and Q4 covers four. Q4's payment is due in January of the following year, which is the one people miss most often — the year has ended, the invoice work has stopped, and the deadline arrives anyway.
If you pay equal quarters against an annual estimate, the uneven periods do not matter. They matter if your income is lumpy and you are annualising, because the IRS looks at what you earned in each period, not the calendar quarter.
What is the safe harbour, and can I legally pay less during the year?
Often yes, and this is the most useful thing on this page after the QBI point. You avoid an underpayment penalty if you pay the lesser of 90% of this year's tax or 100% of last year's total tax. You still owe the full amount — but the balance is not due until you file.
On these inputs, 90% of this year's tax is $25,847, while 100% of last year's is $18,000. The target is therefore $18,000 — you can hold on to the difference until the filing deadline, penalty-free, as long as you have it when the bill arrives.
The multiplier rises to 110% if last year's AGI was above the high-income threshold. This is a cash-flow tool, not a way to pay less tax, and it only helps if you are disciplined enough not to spend the money.
Does my health insurance premium reduce self-employment tax?
No. The self-employed health insurance deduction is an above-the-line deduction against income tax only — it does not reduce net earnings from self-employment, so self-employment tax is charged on that money at the full 14.13%. An employee's premium under a Section 125 plan escapes income tax and FICA both. The freelance hourly rate calculator quantifies what that asymmetry costs over a year.
What happens if I just do not pay quarterly?
You owe an underpayment penalty, calculated as interest on each missed instalment from its due date until you pay. It is not a flat fine — it accrues, so a Q1 shortfall costs more than the same shortfall in Q4. There is a de minimis exception if you owe less than $1,000 at filing.
The practical failure mode is not deliberate. It is a first profitable year: no prior-year tax to safe-harbour against, no withholding, and a bill that arrives in April for money that was spent in July.
Should I elect S-corp status to reduce this?
Possibly, above a certain profit. An S-corp lets you split earnings into a reasonable salary (subject to payroll tax) and distributions (not subject to self-employment tax), which is where the saving comes from. Against that: payroll filings, a separate return, state franchise fees, and the fact that "reasonable salary" is a real standard the IRS enforces.
This calculator models a sole proprietor filing Schedule C, which is what most 1099 workers are. The S-corp comparison depends on facts this tool does not ask for, and it is a genuine accountant conversation rather than a calculator one.
Where these numbers come from
Rates last checked against the sources below on .
Rate schedule version 2026.1, effective .
- IRS Rev. Proc. 2025-32 — inflation adjustments for tax year 2026 retrieved 2026-08-02
- IRS Topic 751 — Social Security and Medicare withholding rates retrieved 2026-08-02
- IRS — COLA increases for dollar limitations on benefits and contributions retrieved 2026-08-02
- IRS Rev. Proc. 2025-19 — 2026 HSA and HDHP inflation adjustments retrieved 2026-08-02
- IRS Publication 15-T — Federal income tax withholding methods
- IRS Form 1040-ES — Estimated tax for individuals