Self-Employed Income Tax Calculator: Build It in Excel

Quick Answer: A self-employed income tax calculator needs five numbers: net profit, self-employment tax (15.3% on 92.35% of net profit, with the 12.4% Social Security part capped at $184,500 for 2026), half of that tax as a deduction, income tax from the 2026 IRS rate schedule, and the total divided by four for quarterly payments. You can build all of it in Excel or Google Sheets with about a dozen formulas.

This guide builds a self-employment tax estimator in a spreadsheet, one cell at a time, using the figures the IRS printed in the 2026 Form 1040-ES package. On $80,000 of net profit, a single filer with no other income lands at roughly $18,830 of federal tax, or about $4,708 per quarter. Every step below shows the formula that gets you there.

This is an estimate, not tax advice. It leaves out credits, state tax and several deductions, which the last section lists. For anything close to a filing decision, check the result against the IRS's own worksheet.

What does a 1099 tax calculator actually compute?

Freelancers, contractors and gig workers who get a 1099 pay two federal taxes on the same profit:

1. Self-employment tax. The IRS describes it on its self-employment tax page as Social Security and Medicare for people who work for themselves: 15.3% in total, made of 12.4% Social Security and 2.9% Medicare. You owe it once net earnings reach $400. It is figured on Schedule SE.
2. Income tax. The ordinary graduated rates, applied to your taxable income after deductions.

The two interact in one place: half of the self-employment tax (the "employer-equivalent portion") is deducted before income tax is figured. That is why a 1099 tax rate is never a single percentage. Someone quoting "30% for freelancers" is averaging these two taxes for a particular income.

Step 1: Put your income and expense totals on an Inputs tab

Create a tab called Inputs with these cells. The labels go in column A, the values in column B.

The expense figure is where most estimates go wrong. A guess like "about a third of revenue" produces a guess of a tax bill. The accurate number comes from summing the year's business transactions by category, which is the job of a self-employed tax spreadsheet organized by Schedule C line. If your records live in bank and card PDFs, QuickBankConvert can turn each statement into dated, signed rows you paste into that sheet, and a SUMIFS by category gives you B3.

The standard deduction for 2026, per the IRS inflation adjustment release, is $16,100 for single filers and married filing separately, $32,200 for married filing jointly, and $24,150 for heads of household.

Step 2: Net profit and the 92.35% adjustment

On a Calc tab:

• B2 Net profit: =Inputs!B2-Inputs!B3 gives 80,000.
• B3 Net earnings from self-employment: =B2*0.9235 gives 73,880.

The 92.35% factor comes straight from line 3 of the 2026 Self-Employment Tax and Deduction Worksheet in Form 1040-ES. It mimics the fact that an employee's wages are not themselves reduced by the employer's half of payroll tax. If B2 is under $400, you owe no self-employment tax at all; wrap later formulas in IF(B2<400,0,…) if you want the sheet to handle that case.

Step 3: Self-employment tax with the Social Security cap

The Social Security part stops at a wage base. The 2026 worksheet prints the maximum as $184,500, and wages you earn as an employee use up part of it first. Medicare has no cap.

• B4 Medicare part: =B3*0.029 gives 2,142.52.
• B5 Room left under the cap: =MAX(0,184500-Inputs!B4) gives 184,500.
• B6 Social Security part: =MIN(B3,B5)*0.124 gives 9,161.12.
• B7 Self-employment tax: =B4+B6 gives 11,303.64.
• B8 Deductible half: =B7*0.5 gives 5,651.82.

The IRS page also notes an Additional Medicare Tax of 0.9% on self-employment income above $200,000 for single filers ($250,000 married filing jointly). It does not apply in this example. If your profit is near those levels, add a cell for it.

How do you calculate income tax from the IRS brackets in a spreadsheet?

First the taxable income:

• B9 Adjusted gross income: =B2-B8 gives 74,348.18.
• B10 Taxable income: =MAX(0,B9-Inputs!B6) gives 58,248.18.

Then put the 2026 single-filer rate schedule (Schedule X in the 1040-ES package) on a Brackets tab. Column A is the lower bound, B is the tax on income up to that bound, C is the rate:

The formula uses approximate-match lookup, which finds the last row whose lower bound is at or below your income:

B11 Income tax: =VLOOKUP(B10,Brackets!A2:C8,2,TRUE)+(B10-VLOOKUP(B10,Brackets!A2:A8,1,TRUE))*VLOOKUP(B10,Brackets!A2:C8,3,TRUE)

For 58,248.18 it picks the 50,400 row: 5,800 + (58,248.18 − 50,400) × 22% = 7,526.60. The same formula works in Google Sheets. In Excel 365 you can swap VLOOKUP for XLOOKUP(B10,Brackets!A2:A8,Brackets!B2:B8,,-1), where the -1 means "exact match or next smaller".

If you file jointly, build a second table from Schedule Y-1 (the 12% bracket starts at $24,800, the 22% at $100,800, and so on) and pick the table with IF(Inputs!B5="Married filing jointly",…).

Step 4: Total, effective rate and quarterly split

• B12 Total federal tax: =B7+B11 gives 18,830.24.
• B13 Effective rate on net profit: =B12/B2 gives 23.5%.
• B14 Still to pay: =MAX(0,B12-Inputs!B7).
• B15 Each quarterly payment: =B14/4 gives 4,707.56.

The 2026 voucher due dates printed in Form 1040-ES are April 15, 2026, June 15, 2026, September 15, 2026 and January 15, 2027. The January payment can be skipped if you file your 2026 return by February 1, 2027 and pay the full balance with it. Put those dates in a small table next to B15 and log each payment as you make it; tracking estimated payments against your bank statements shows how to prove each one later.

Do you have to pay the full calculated amount each quarter?

Not necessarily. The IRS estimated taxes page says individuals generally must pay estimated tax if they expect to owe $1,000 or more, and that most people avoid the underpayment penalty by paying at least 90% of this year's tax or 100% of last year's, whichever is smaller. The 1040-ES instructions raise the prior-year figure to 110% if your prior-year AGI was over $150,000 ($75,000 married filing separately).

That gives the sheet a second, often lower, target. Add:

• B16 Prior-year total tax (from last year's Form 1040): typed in.
• B17 Safe-harbor target: =MIN(B12*0.9,B16*IF(prior_AGI>150000,1.1,1)).
• B18 Safe-harbor quarterly payment: =B17/4.

When income is rising, paying B18 instead of B15 keeps cash in your account during the year, at the price of a larger balance due in April.

Running the calculator through the year

A once-a-year estimate drifts as soon as a big client pays late or a slow month arrives. A simple routine keeps it honest:

1. At each quarter end, replace B2 and B3 with year-to-date totals from your statements.
2. Add an Annualize cell: =B2/months_elapsed*12, and point the tax formulas at it.
3. Subtract payments already made (B7 on the Inputs tab) and recompute the remaining quarters.

The IRS page on estimated taxes allows exactly this: if you estimated too high or too low, you refigure with a fresh worksheet before the next payment. The quarterly bank statement workflow covers the bookkeeping side of that routine, from downloading statements to coding each row.

What this self-employed estimator leaves out

A spreadsheet of these few formulas is accurate for a simple return and wrong for a complicated one. It does not include:

• The qualified business income deduction, which many sole proprietors can take (Form 1040-ES has a line for it). Read the current IRS rules before adding it.
• The self-employed health insurance deduction and retirement contributions such as a SEP or Solo 401(k).
• Credits (child tax credit, education credits and others) and other income such as interest, dividends or a spouse's wages.
• State and local income tax, which most states also collect by estimated payments.

For a fuller check, the IRS's Form 1040-ES page links the worksheet this sheet is modelled on, and Publication 505 explains the edge cases. A tax professional is the right call if you have several businesses, an S corporation, or large one-off income.

Related guides

• Freelancer tax prep: sorting bank statements and 1099s
• Gig drivers' bank statement records
• Converting statement PDFs to Excel