The basic formula for estimated taxes
To calculate what you owe in estimated taxes, multiply your expected annual income by your tax rate, then divide by four. The result is one quarterly payment. The formula is: (Expected annual income × Tax rate) ÷ 4 = One quarterly payment.
The tricky part is knowing your tax rate. If you are self-employed, you owe both income tax and self-employment tax (Social Security and Medicare). If you are a W-2 employee with side income, you only owe income tax on the side income. The rate depends on your total income for the year and your filing status.
Start by estimating your total income for the year — wages, business income, rental income, investment gains, or anything else taxable. Then look up the tax bracket that matches your income and filing status on the IRS tax tables. That is your marginal rate, not your effective rate. Use the marginal rate because it applies to the income you are estimating.
Key Takeaways
- Divide your expected annual income by your tax rate, then divide by four to find one quarterly payment amount.
- Self-employed people owe both income tax and self-employment tax (15.3% combined on net profit), while W-2 employees with side income owe only income tax.
- Use the IRS tax tables to find your marginal tax rate based on your total expected income and filing status, not your effective rate.
- Payments are due April 15, June 15, September 15, and January 15 of the following year, and missing a deadline can result in penalties even if you owe nothing at tax time.
Self-employment tax adds to your bill
If you are self-employed, your estimated tax payment includes two parts: income tax and self-employment tax. Self-employment tax covers Social Security and Medicare and is calculated on your net profit (income minus business expenses). The rate is 15.3% — 12.4% for Social Security and 2.9% for Medicare.
To calculate self-employment tax, take your expected net profit for the year and multiply by 0.153. Then add your income tax on that same profit. For example, if you expect $50,000 in net profit and you are in the 22% tax bracket, your self-employment tax is $7,650 and your income tax is $11,000, for a total of $18,650 per year, or $4,662.50 per quarter.
You can deduct half of your self-employment tax from your income before calculating income tax, which lowers your bill slightly. The IRS worksheet for Form 1040-ES walks through this deduction step by step.
W-2 employees with side income
If you have a regular job with W-2 withholding and also earn side income, you do not owe self-employment tax on the side income — only income tax. Calculate estimated taxes on the side income alone, not your total household income.
Estimate your side income for the year, find your marginal tax rate based on your total household income (W-2 plus side income), and multiply the side income by that rate. Divide by four for your quarterly payment. For example, if you earn $60,000 on a W-2 and expect $15,000 in freelance income, and your marginal rate is 22%, your estimated tax on the side income is $3,300 per year, or $825 per quarter.
Before you commit to quarterly payments, check whether your W-2 withholding already covers the tax on your side income. If your employer withholds more than you owe, you may not need to pay estimated taxes at all.
Using IRS Form 1040-ES to organize your calculation
The IRS provides Form 1040-ES, the Estimated Tax for Individuals form, which includes worksheets and tax tables. You do not file this form — it is a worksheet only. The form walks you through estimating income, calculating tax, and determining your quarterly payment amount.
The form has four worksheets. Worksheet 1 estimates your income and deductions. Worksheet 2 calculates your tax using the tax tables in the form. Worksheet 3 accounts for tax credits. Worksheet 4 figures out whether you need to make estimated payments at all. Most people use Worksheets 1 and 2 and skip the rest.
Download Form 1040-ES from IRS.gov. The form changes each year because tax brackets adjust for inflation. Use the current year's version, not last year's.
Adjusting for income that varies month to month
If your income is uneven — high some months and low others — you can use the annualized income method instead of dividing your annual estimate by four. This method calculates tax based on actual income through each quarter, which can lower your payment if you had a slow start to the year.
To use the annualized method, calculate your actual income and tax through the end of each quarter, then subtract tax already paid. The difference is your payment for that quarter. This requires more bookkeeping but can save money if your income is seasonal or cyclical.
Form 1040-ES includes a worksheet for the annualized method. Most people use it only if their income is significantly uneven — for example, if they earn most of their money in the fall or winter.
Quarterly payment deadlines and where to send payment
Estimated tax payments are due on four dates each year: April 15, June 15, September 15, and January 15 of the following year. These dates do not move if they fall on a weekend or holiday — the IRS extends the deadline only if the date falls on a federal holiday in Washington, D.C., which is rare.
You can pay online through IRS.gov using the Electronic Federal Tax Payment System (EFTPS), by credit or debit card through an approved payment processor, by mail with a check or money order, or by phone. Online payment is fastest and gives you a confirmation number immediately. Mail payments take 7 to 10 business days to post.
If you miss a deadline, you owe a penalty and interest on the late amount, even if you end up overpaying for the year. The penalty is calculated from the due date, not from the date you file your tax return. Pay as soon as you realize you are late.
What to do if your income changes mid-year
If you earn significantly more or less than you estimated, recalculate your remaining quarterly payments. You are not locked into your first estimate. Recalculate after each quarter using your actual income so far plus a revised estimate for the rest of the year.
For example, if you estimated $50,000 in annual income and paid $3,125 per quarter, but by June you have already earned $30,000, recalculate. If you now expect $70,000 for the year, your new quarterly payment is higher. Pay the difference with your next payment. If you expect less, your next payment can be lower.
Recalculating quarterly keeps you from overpaying or underpaying by year-end. It also reduces the risk of owing a penalty for underpayment.
Frequently Asked Questions
What if I do not know my income for the year?
Use your income from last year as a starting point, then adjust up or down based on what you know so far. If last year you earned $40,000 and this year looks similar, estimate $40,000. If you expect a big project or a slow period, adjust accordingly. Your estimate does not have to be exact — it just needs to be reasonable.
Can I pay more than one quarter at once?
Yes. You can pay all four quarters at once, or pay two quarters together, or pay any combination. The only requirement is that each quarter's payment is due by its deadline. Paying early does not hurt, and it can simplify your bookkeeping.
Do I owe estimated taxes if I expect to break even or lose money?
No. Estimated taxes are based on expected profit or income. If you expect to break even or have a loss, you do not owe estimated taxes. However, if you have other income (wages, investment gains, rental income), you may still owe estimated taxes on that.
What happens if I overpay estimated taxes?
The overpayment carries forward to your tax return. When you file, the IRS credits the overpayment against what you owe, or refunds it to you if you overpaid overall. There is no penalty for overpaying.
Do I need to make estimated payments if my employer withholds taxes?
Only if your withholding does not cover your total tax bill. If you have a W-2 job and side income, check whether your W-2 withholding covers tax on both. If it does, you may not need estimated payments. If it does not, you owe estimated taxes on the shortfall.