1099/Side-Hustle Quarterly Estimated Tax Calculator
Self-employment tax comes on top of income tax, not instead of it
1099/Side-Hustle Quarterly Estimated Tax Calculator
Self-employment tax (15.3%)
0
on 92.35% of net income
Income tax on net SE income
0
Quarterly estimated payment
0
1 of 4 equal payments
Self-employment tax is on top of income tax, not instead of it
The 15.3% SE tax (Social Security plus Medicare, both the "employer" and "employee" halves since you're both) applies BEFORE income tax, on 92.35% of net self-employment income — a surprise for people used to seeing only their W-2 FICA withholding.
Missing quarterly payments has a real interest cost
The IRS expects roughly even payments across the year's 4 due dates (mid-April, mid-June, mid-September, mid-January) — paying it all at filing time instead risks Section 234B/2210-equivalent underpayment penalties even if the total is right.
W-2 withholding can cover 1099 tax too
If you also have a W-2 job, increasing your W-2 withholding (via a new W-4) can cover your side-hustle tax liability without filing separate quarterly vouchers — often simpler than tracking 4 estimated payments yourself.
Self-employment tax modeled at the standard 15.3% (12.4% Social Security plus 2.9% Medicare) on 92.35% of net income (gross minus deductible expenses), ignoring the Social Security wage base cap for simplicity (income above the annual SS wage base only owes the 2.9% Medicare portion, not the full 15.3% — a real reduction at higher income levels not modeled here) and ignoring the Additional Medicare Tax (0.9% above $200K single/$250K joint). Income tax applies your marginal rate to net income after the standard half-SE-tax deduction. Quarterly payment simply divides the annual total by 4 minus your W-2 withholding credit — real safe-harbor rules (100%/110% of last year's tax) can differ from this straightforward current-year estimate. Not tax advice.
Frequently asked questions
How do federal tax brackets actually work?
The US uses a progressive, marginal system -- only the income within each bracket is taxed at that bracket's rate, not your entire income at your top rate. This is why your effective (average) tax rate is always lower than your marginal (top) bracket rate, a distinction this calculator shows explicitly.
What's the difference between a tax deduction and a tax credit?
A deduction reduces your taxable income before tax is calculated, so its value depends on your bracket. A credit reduces your tax bill directly, dollar for dollar, regardless of bracket -- which generally makes credits more valuable than a deduction of the same nominal size.
How is capital gains tax calculated on stocks/funds?
Assets held over one year qualify for long-term capital gains rates, which are generally lower than ordinary income tax rates; assets held one year or less are taxed as short-term gains at your regular income tax rate. Holding period alone can meaningfully change the tax owed on the same gain.
Should I contribute to a traditional or Roth account?
Traditional accounts (401(k), IRA) give you a tax deduction now and are taxed on withdrawal in retirement; Roth accounts are funded with after-tax money now and grow completely tax-free. Broadly, if you expect to be in a lower tax bracket in retirement than today, traditional tends to win, and vice versa for Roth -- this calculator lets you compare both with your own numbers.
Estimates only, not financial advice. See our Disclaimer.
