What this Estimated Quarterly Tax Calculator does
If you're self-employed, a freelancer, or run a small business, the IRS expects you to pay estimated taxes four times a year rather than once at filing. Missing or underpaying those installments can trigger an underpayment penalty even if you get a refund in April. This English-language calculator covers both federal estimated income tax and self-employment (SE) tax — the 15.3% FICA equivalent that sole proprietors pay on net earnings — so you see the full picture in one place. Results appear instantly in your browser. Your income figures, deductions, and filing status are never transmitted to any server. As noted in RFC 8259, data integrity starts with keeping data local — 100% client-side means your data never leaves your browser. No uploads, no tracking, no server logs.
Features
- Federal income tax estimate. Applies current IRS marginal brackets to your projected annual net income, then divides the result into four equal quarterly tax payment amounts.
- Self-employment tax calculation. Computes the 15.3% SE tax on 92.35% of net self-employment earnings, and factors in the deductible half when estimating your income tax base.
- Safe-harbor check. Flags whether your planned payments meet the IRS safe-harbor threshold (100% of prior-year tax, or 110% if AGI exceeded $150,000), helping you avoid underpayment penalties.
- Estimated quarterly tax due dates. Displays the standard IRS due dates for each tax quarter — typically April 15, June 16, September 15, and January 15 — so you can schedule payments in advance.
- 1040-ES payment summary. Shows a breakdown formatted to match Form 1040-ES lines, making it straightforward to reconcile your estimate with the IRS voucher. For planning long-term savings alongside taxes, the [compound interest calculator](/en/compound-interest-calculator/) is a natural companion.
- No sign-up, no tracking. Every calculation runs entirely in your browser. Close the tab and nothing is stored — no account required, no session data retained.
How to use the Estimated Quarterly Tax Calculator
Enter your numbers, hit Calculate, and your per-quarter payment appears immediately. No forms to submit, no email required.
- Enter your projected annual net income. Type your expected self-employment net profit for the year. If you're mid-year, use your year-to-date figure and project forward.
- Select your filing status. Choose Single, Married Filing Jointly, or Head of Household. This determines which federal tax brackets apply to your income.
- Add any deductions. Enter above-the-line deductions such as the self-employed health insurance deduction or contributions to a SEP-IRA to reduce your taxable income.
- Review the quarterly breakdown. The calculator shows the estimated tax due for each tax quarter alongside the IRS due date. You can copy the result and paste it into a spreadsheet or your accounting tool.
- Make your IRS estimated tax payment. Use the output to complete Form 1040-ES or pay directly via the IRS Direct Pay portal. Keeping a record of each payment date protects you if the IRS questions a prepay taxes submission.
Common use cases
- Freelancers and consultants. Developers, designers, and writers in cities like Austin or Seattle who invoice clients directly often have no employer withholding. This calculator translates a project pipeline into concrete quarterly payment amounts.
- Side-business owners. Someone running an e-commerce store or a rental alongside a W-2 job needs to estimate the extra federal estimated income tax owed on that side income — this tool isolates it cleanly.
- First-year self-employed filers. When you have no prior-year tax liability to base safe-harbor on, estimating quarterly taxes from scratch is daunting. The calculator walks through the math so you don't underpay or overpay significantly.
- S-corp owners taking distributions. Owners who pay themselves a salary plus distributions need to model the SE tax only on the salary portion. Adjusting the net earnings input here shows the difference quickly.
- Tax professionals and bookkeepers. Accountants preparing quarterly tax payment estimator worksheets for clients can run scenarios fast — changing income or deduction assumptions — without touching sensitive data in a cloud tool.
Frequently asked questions
How is the self-employment tax calculated?
SE tax is 15.3% (12.4% Social Security + 2.9% Medicare) applied to 92.35% of your net self-employment earnings. The 92.35% factor accounts for the employer-equivalent deduction. You can then deduct half of the SE tax when calculating your adjusted gross income for federal income tax purposes.
What are the estimated quarterly tax due dates for 2025?
The IRS sets four payment deadlines per year. For most years: April 15 (Q1), June 16 (Q2), September 15 (Q3), and January 15 of the following year (Q4). If a date falls on a weekend or holiday it shifts to the next business day. Check IRS.gov for the exact calendar each year.
What happens if I underpay estimated taxes?
The IRS charges an underpayment penalty computed on the shortfall for each quarter. You avoid it by meeting the safe-harbor rule: paying at least 100% of last year's tax liability (or 110% if your prior-year AGI exceeded $150,000). The penalty is separate from any tax you still owe at filing.
Is my financial data safe when I use this calculator?
Yes. All calculations happen entirely in your browser using JavaScript — nothing is sent to a server. This is the same principle behind well-designed local-first tools: as described in RFC 4122 for identifier generation, good software design defaults to local processing. Your income figures are never logged, stored, or transmitted.
Can I pay estimated taxes directly online?
Yes. The IRS accepts online payments through IRS Direct Pay (bank transfer, free) and EFTPS (requires registration). You can also mail a check with a 1040-ES voucher. EFTPS is particularly useful if you want to schedule all four quarterly payments in advance. This calculator gives you the amounts; the IRS portal handles the actual transfer.
How does this differ from TurboTax's estimated tax feature?
TurboTax's pay estimated taxes workflow is bundled inside a paid product and requires an account. This calculator is standalone, free, and runs client-side — useful when you just want a quick quarterly tax payment estimator without logging into a full tax suite. For modeling how your savings grow alongside tax planning, the [Investment ROI Calculator](/en/investment-roi-calculator/) pairs well.