Monster Quarterly Estimated Tax Calculator
Self-employed? The IRS wants its cut four times a year. Enter your expected annual profit and tax bracket to estimate each quarterly payment — covering both self-employment tax and federal income tax.
| Self-employment taxable earnings (92.35%) | $0 |
| Self-employment tax (15.3%) | $0 |
| Federal income tax | $0 |
| Total annual tax | $0 |
How it works
Two taxes apply to self-employment income. Self-employment tax = profit × 0.9235 × 15.3% (covers Social Security + Medicare). Federal income tax = profit × your marginal bracket. Total annual tax = SE tax + income tax, and each quarterly payment = total ÷ 4.
Formula & worked example
Formula: Self-employment tax = profit × 92.35% × 15.3% — only 92.35% of profit is subject to SE tax. Income tax = profit × your chosen bracket %. The annual estimate is the sum of the two, and each quarterly payment is a quarter of it.
Worked example: On $80,000 of profit in the 22% bracket: SE tax is $73,880 × 15.3% = $11,304 and income tax is $17,600, totalling $28,904 a year — four quarterly payments of $7,226.
When to use this
- You left a W-2 job for freelancing or contracting and nobody is withholding tax from your pay any more.
- Your side business started making real profit and you need a quarterly figure before the next due date, not at filing time.
- Your income jumped this year and last year's payment amounts no longer look safe.
- You want to see how much of each client payment to move into a tax savings account as it arrives.
How to use it, step by step
- Enter your expected annual net profit — revenue minus business expenses, not gross billings.
- Set the marginal federal income tax rate for your bracket.
- Read the self-employment tax, the income tax and the total, then the quarterly payment, which is the total divided by four.
- Re-run it whenever your profit forecast changes materially; estimates are meant to be revised during the year.
- Treat the result as a planning estimate and confirm the final figures with a tax professional — state tax, deductions and credits are not in this model.
What the inputs mean
| Input | What it is | Typical values |
|---|---|---|
| Expected annual net profit | Self-employment revenue minus business expenses for the year | Part-time freelancing $10k–$40k; full-time often $50k–$150k+ |
| Marginal federal income tax rate | The bracket rate you pick for the income-tax part of the estimate | Common brackets used here: 12%, 22%, 24% |
Another worked example
A freelancer expecting $55,000 of net profit in the 12% bracket: the self-employment taxable base is $50,793 (92.35% of profit), self-employment tax comes to $7,771, and federal income tax at 12% adds $6,600. The total annual estimate is $14,371, split into four quarterly payments of $3,593 as the tool displays them — each figure rounded to whole dollars the way the tool formats it.
Frequently asked questions
Who has to pay estimated taxes quarterly?
Generally, anyone who expects to owe $1,000 or more in tax after withholding and credits. Most freelancers, contractors, and small business owners qualify — employees with enough W-2 withholding usually don't.
When are the quarterly deadlines?
For 2026: April 15, June 15, September 15, 2026, and January 15, 2027. If a date falls on a weekend or holiday, the deadline shifts to the next business day.
What happens if I underpay?
The IRS can charge an underpayment penalty plus interest. Safe harbors: pay at least 90% of this year's tax or 100% of last year's tax (110% if your AGI was over $150,000) through quarterly payments and withholding.
Does this estimate include my state taxes?
No. It covers only the two federal pieces — self-employment tax at 15.3% on 92.35% of profit, and federal income tax at the bracket rate you enter. Most states with an income tax expect their own estimated payments on top, so budget separately for those.
Why does the real return often come out lower than this estimate?
This model is deliberately simple: it applies your bracket rate to the full profit and does not subtract the standard deduction, the deduction for half of self-employment tax, business credits or the qualified business income deduction. Those all reduce a real liability, so treat this figure as a cautious planning estimate, not a prediction of your filed return — and not tax advice.
What if I also have a W-2 job during the year?
Tax withheld by an employer counts toward the same annual bill, so a W-2 job covering part of the year usually means smaller quarterly payments are needed than this full-profit estimate suggests. Some people instead raise their W-2 withholding to cover side income and skip quarterly vouchers; either way, the combined total paid in is what matters at filing.