What you actually owe
each quarter — and when.

How it works

Nobody withholds taxes for you — until you do it yourself.

A W-2 employee never thinks about estimated taxes because payroll handles it automatically, every pay period. Self-employment income has no equivalent: nothing is withheld unless you set it aside and send it in yourself, four times a year, on a schedule the IRS sets rather than one that matches when your income actually shows up. Getting the number wrong in either direction has a real cost — underpay and risk a penalty, overpay and give the IRS an interest-free loan until you file.

Self-employment tax: Social Security + Medicare, on your own

As a self-employed person, you're both the employee and the employer for Social Security and Medicare purposes, which is why self-employment (SE) tax runs 15.3% instead of the 7.65% a paycheck shows. It's calculated on 92.35% of your net profit — a built-in adjustment that roughly mirrors how a W-2 employee's employer-paid half isn't itself subject to the tax. The Social Security portion (12.4%) stops once your combined wages and SE earnings hit the annual wage base ($184,500 for 2026); the Medicare portion (2.9%) has no cap at all.

The Additional Medicare Tax most people miss

Above $200,000 (single/head of household) or $250,000 (married filing jointly) in combined wages and SE income, an extra 0.9% Additional Medicare Tax applies on top — and unlike most tax thresholds, this one is fixed by statute and does not adjust for inflation year to year. It's calculated on the same 92.35%-reduced SE figure, not your gross profit.

A worked example

A single freelancer with $60,000 in net Schedule C profit and no other income: SE tax base is $55,410 (92.35% of $60,000). Social Security tax is $6,870.84, Medicare tax is $1,606.89, for $8,477.73 in total SE tax. Half of that — $4,238.87 — is deducted above the line before federal income tax is calculated, bringing taxable income (after the $16,100 standard deduction) to $39,661.14 and federal income tax to $4,511.34. Combined current-year tax: $12,989.07. With no prior-year tax entered, the required annual payment is 90% of that — $11,690.16 — or $2,922.54 per quarter.

Safe harbor: paying based on last year instead of guessing this year

If this year's income is hard to predict, the IRS lets you pay based on a known number instead: 100% of last year's total tax (110% if your prior-year AGI topped $150,000), rather than 90% of a current-year estimate you can't be fully sure of yet. You only need to clear the smaller of the two tests to avoid a penalty — so a freelancer expecting a much bigger year than last year can lock in a lower, known payment using the prior-year figure instead.

Disclaimer

This calculator provides an educational estimate based on 2026 IRS and SSA figures and does not replace Form 1040-ES's own worksheet, a licensed CPA, or a tax attorney. It assumes reasonably even income across the year — see the FAQ on lumpy income for the annualized-income-installment method this tool doesn't attempt — and does not account for state estimated taxes, tax credits, capital gains, or the Net Investment Income Tax.