Quarterly Estimated Tax Calculator
Estimate your 2026 quarterly estimated tax payments with the Form 1040-ES worksheet, safe-harbor comparison, annualized income method, and underpayment penalty estimate.
Built from IRS Publication 505, Form 1040-ES, Form 2210 instructions, and the IRS quarterly interest rates.
Quarterly payment
2026$0
per quarter
Advanced inputs W-2 wages, other income, QBI, other taxes
Box 3 of your W-2. Coordinates the SS wage base.
Box 5 of your W-2. Coordinates the Additional Medicare threshold.
Interest, dividends, W-2 wages (box 1), capital gains, etc. NIIT is not computed.
User-entered. $400 minimum if QBI is at least $1,000.
Additional Medicare Tax, NIIT, etc.
Enter only if your itemized deductions exceed the standard deduction.
Enter actual payments to estimate the underpayment penalty.
These inputs are optional. The calculator uses the standard deduction by default and does not model AMT, NIIT, or the itemized deduction limitation. Enter actual quarterly payments to estimate the underpayment penalty.
Payment schedule
| Period | Due date | Payment | Cumulative |
|---|
Tax breakdown
This is an estimate, not tax advice. It computes federal quarterly estimated tax for planning. Your filed return can differ based on credits, deductions, and state rules. Confirm anything material with a CPA or enrolled agent.
The basics
What this calculator does
The federal income tax is a pay-as-you-go system. If you're self-employed, you generally need to make four estimated tax payments throughout the year, because your business income doesn't have tax withheld the way W-2 wages do. This calculator walks through the Form 1040-ES worksheet step by step, compares the safe harbors, handles variable income with the annualized method, and estimates the underpayment penalty if you underpay.
Estimated tax
The pay-as-you-go tax you send to the IRS throughout the year if your income doesn't have enough withholding. For self-employed people, this covers both income tax and self-employment tax.
Form 1040-ES
The IRS form and worksheet you use to figure your estimated tax. It walks through your expected income, deductions, tax, and the required annual payment, then divides by four for your quarterly amount.
Safe harbor
A rule that lets you avoid the underpayment penalty if you pay at least the smaller of 90% of your current-year tax or 100% of your prior-year tax (110% if your prior-year AGI was over $150,000).
Required annual payment
The smaller of 90% of your current-year total tax or 100%/110% of your prior-year total tax. This is the amount you need to prepay through withholding and estimated tax to avoid a penalty.
Annualized income installment method
A method for variable income that recomputes each quarterly payment based on your actual income through the end of each period. It uses IRS annualization factors to project your full-year tax from partial-year income.
Form 2210
The IRS form where you figure the underpayment penalty. The penalty is computed separately for each installment period, based on the IRS quarterly interest rate and the number of days the underpayment remains unpaid.
Underpayment penalty
An interest charge on the amount you underpaid for each quarter. The rate is the federal short-term rate plus 3 percentage points, set quarterly by the IRS. For 2026, the rates are 7%, 6%, and 7% for the first three quarters.
Self-employment tax
The Social Security and Medicare tax (15.3% combined) that self-employed people pay on net business profit. It's part of your total tax and must be included in your estimated tax payments.
Deductible half of SE tax
An above-the-line deduction equal to 50% of your self-employment tax (excluding Additional Medicare Tax). It reduces your adjusted gross income, which in turn lowers your income tax.
De minimis exception
A rule that waives the estimated tax requirement entirely if your total tax minus withholding is less than $1,000. You also don't have to pay estimated tax if you had no tax liability in the prior year.
The math
The formula, and the order it runs in
The calculator follows the Form 1040-ES Estimated Tax Worksheet (Worksheet 2-1 in Publication 505). Here's the order of operations.
Quarterly payment = (Required annual payment − Withholding) ÷ 4
Where: Required annual payment = min(90% of current-year total tax, 100%/110% of prior-year total tax)
Compute total tax
Add income tax, self-employment tax, and other taxes to get your total estimated tax (Form 1040-ES Worksheet 2-1, line 11c).
90% of current year
Multiply your total estimated tax by 90% to get the first safe harbor (line 12a).
100%/110% of prior year
Take 100% of your prior-year total tax, or 110% if your prior-year AGI was over $150,000 (line 12b).
Required annual payment
Enter the smaller of the two safe harbors as your required annual payment (line 12c).
Subtract withholding
Subtract your expected withholding from the required annual payment (line 14a).
Divide by 4
Divide the result by 4 to get your quarterly payment amount (line 15).
Worked examples
How it plays out at different income levels
$60,000 net SE profit, single filer, 2026. Prior-year total tax was $10,000; prior-year AGI was $50,000.
- Total estimated tax$12,989.07
- 90% of current year$11,690.16
- 100% of prior year$10,000.00
- Required annual payment$10,000.00
- Quarterly payment$2,500.00
$200,000 net SE profit, married filing jointly, 2026. Prior-year total tax was $40,000; prior-year AGI was $180,000 (above $150,000).
- Total estimated tax$51,468.53
- 90% of current year$46,321.68
- 110% of prior year$44,000.00
- Required annual payment$44,000.00
- Quarterly payment$11,000.00
$5,000 net SE profit, single filer, 2026. Total tax minus withholding is under $1,000.
- Total estimated tax$706.48
- Total tax minus withholding$706.48
- Under $1,000 thresholdYes
- Payments requiredNo
$60,000 net SE profit, single filer, 2026. $4,000 federal income tax withheld from a W-2 job. Prior-year total tax was $10,000; prior-year AGI was $50,000.
- Total estimated tax$12,989.07
- Required annual payment$10,000.00
- Minus withholding$4,000.00
- Total estimated payments$6,000.00
- Quarterly payment$1,500.00
The form
How the result flows to your tax return
Your quarterly estimated tax payments don't appear on your tax return as a single line. The computation happens on the Form 1040-ES worksheet, and the payments are made via vouchers or online. When you file, the total goes on Form 1040, line 26. If you underpay, Form 2210 computes the penalty.
Straightforward case
$60,000 net SE profit, single, 2026. Prior-year tax $10,000, prior-year AGI $50,000.
| Form | Line | Description | Amount |
|---|---|---|---|
| Form 1040-ES Worksheet 2-1 | Line 11c (total tax) | Income tax + SE tax | $12,989 |
| Form 1040-ES Worksheet 2-1 | Line 12c (required payment) | Smaller of 90% or 100% prior | $10,000 |
| Form 1040-ES voucher | Q1-Q4 payment | Line 12c / 4 | $2,500 |
Higher income, 110% safe harbor
$200,000 net SE profit, MFJ, 2026. Prior-year tax $40,000, prior-year AGI $180,000.
| Form | Line | Description | Amount |
|---|---|---|---|
| Form 1040-ES Worksheet 2-1 | Line 11c (total tax) | Income tax + SE tax | $51,469 |
| Form 1040-ES Worksheet 2-1 | Line 12b (110% prior) | 110% of $40,000 | $44,000 |
| Form 1040-ES voucher | Q1-Q4 payment | Line 12c / 4 | $11,000 |
Sole proprietors and single-member LLCs. This mapping is for Schedule C filers using the regular installment method. If you use the annualized income installment method, you must file Form 2210 with your return. The calculator shows cent-precision figures for planning; your actual filed forms round to whole dollars.
Watch out
Common mistakes to avoid
- Using a flat 30% set-aside instead of computing the actual tax with brackets, deductions, and SE tax.
- Forgetting the prior-year safe harbor which can be much lower than 90% of current-year tax if your income dropped.
- Not including self-employment tax in the total tax figure, leading to underpayment.
- Missing the $1,000 de minimis exception which waives the requirement for small tax amounts.
- Paying equal amounts with variable income instead of using the annualized method to match your cash flow.
- Ignoring the January payment exception which lets you skip the Q4 payment if you file by January 31.
Behind the answer
How I tested the quarterly estimated tax calculator
I tested this calculator against 16 test cases covering total tax computation, safe harbor comparison, quarterly installments, the de minimis and no-prior-year-liability exceptions, due dates, the annualized income installment method, penalty estimation, validation, and share URL round-trip. Each test case traces back to a specific IRS source.
Total tax computation
I verified the full Form 1040-ES Worksheet 2-1 across four filing statuses and multiple income levels, including the Social Security wage base cap and Additional Medicare Tax.
Safe harbors and exceptions
The 90% current-year and 100%/110% prior-year safe harbors are tested side by side. The $1,000 de minimis exception and the no-prior-year-liability exception are both covered.
Annualized income method
The annualization factors (4, 2.4, 1.5, 1), applicable percentages (22.5%, 45%, 67.5%, 90%), and per-period SE tax computation are tested against Worksheet 2-9.
Penalty and validation
The underpayment penalty uses 2026 IRS quarterly interest rates. Validation catches non-numeric inputs, negative values, and missing filing status. Share URL round-trip is tested.
Every test case traces back to the Form 1040-ES worksheet, safe-harbor rule, or IRS interest rate it came from. You can download all 16 test cases as JSON and check any payment against the cited source. If you spot a result that doesn't match, tell me and I'll fix it.
FAQ
Questions people ask
Who has to pay quarterly estimated taxes?
You must make estimated tax payments if you expect to owe at least $1,000 in tax after subtracting withholding and credits, and your withholding and credits will be less than 90% of your current-year tax or 100% of your prior-year tax (110% if your prior-year AGI was over $150,000). Self-employed people generally meet this threshold because they don't have tax withheld from their business income.
How much should I pay each quarter?
Your quarterly payment is one-fourth of your required annual payment, which is the smaller of 90% of your current-year total tax or 100%/110% of your prior-year total tax. This calculator computes both safe harbors and shows you the smaller one, then divides by four.
What are the safe harbors?
The safe harbors are rules that let you avoid the underpayment penalty. You meet a safe harbor if you prepay at least 90% of your current-year tax, or 100% of your prior-year tax (110% if your prior-year AGI was over $150,000, or $75,000 if married filing separately). You can also avoid the penalty if your total tax minus withholding is under $1,000, or if you had no tax liability in the prior year.
What happens if I underpay?
If you don't pay enough by each due date, you may owe an underpayment penalty. The penalty is an interest charge computed separately for each installment period, based on the IRS quarterly interest rate and the number of days the underpayment remains unpaid. For 2026, the rates are 7% (Q1), 6% (Q2), and 7% (Q3). The Q4 rate has not been published yet.
When are the quarterly due dates?
For calendar-year 2026, the due dates are April 15, 2026; June 15, 2026; September 15, 2026; and January 15, 2027. If a due date falls on a weekend or legal holiday, the deadline shifts to the next business day.
Can I pay different amounts each quarter?
Yes. If your income varies throughout the year, you can use the annualized income installment method (Form 2210 Schedule AI). This method recomputes each payment based on your actual income through the end of each period, so your payments match your cash flow. This calculator supports the annualized method as a mode toggle.
How does self-employment tax factor in?
Self-employment tax is part of your total tax and must be included in your estimated tax payments. This calculator calls the CalcWise self-employment tax engine to compute your SE tax (including the Social Security wage base and Additional Medicare Tax), then adds it to your income tax to get your total estimated tax.
What if I also have a W-2 job?
If you have W-2 wages, enter your withholding in the main inputs and your W-2 Social Security and Medicare wages in the Advanced section. Withholding reduces your required estimated tax payments, and your W-2 Social Security wages coordinate with the SE tax wage base.
Can I skip the January payment if I file early?
Yes. If you file your 2026 Form 1040 by January 31, 2027, and pay the rest of the tax you owe, you don't need to make the January 15, 2027 payment. Your fourth installment is considered paid on time. However, you may still owe a penalty for the first three installments if they were underpaid.
What if my income varies throughout the year?
Use the annualized income installment method. Enter your income for each period (January through March, April through May, June through August, and September through December). The calculator annualizes your income at the end of each period and computes the required payment based on the IRS annualization factors and applicable percentages (22.5%, 45%, 67.5%, 90%).
What this calculator doesn't model (and why)
State quarterly payments
Most states have their own estimated tax requirements. This calculator is federal only; check your state's rules separately.
Full QBI deduction (Section 199A)
The QBI deduction is user-entered. The full calculation (SSTB classification, W-2 wage limits, phase-in ranges) is not modeled. A separate QBI calculator is planned.
Itemized deduction limitation
The 2026 itemized deduction reduction and the SALT cap are not modeled. Use the standard deduction for the most accurate result.
AMT and NIIT
Alternative Minimum Tax and Net Investment Income Tax are not computed. If you have investment income or AMT exposure, consult a CPA.
Farmers and fishermen
Special rules for farmers and fishermen (Form 2210-F: 66.67% safe harbor, single January 15 payment) are not modeled.
Q4 2026 underpayment rate
The Q4 2026 IRS underpayment interest rate has not been published yet. The calculator uses 7% (the Q3 rate) as a placeholder and displays a warning.
Simplified penalty estimate
The penalty calculation assumes the full underpayment for each quarter remains unpaid for the entire rate period. If you make partial payments during a period, the actual penalty will be lower. This is a planning estimate, not a filed Form 2210 computation.
Updates
What's changed
- Built the calculator with 2026 tax brackets, standard deduction, and safe-harbor rules. Confirmed the 2026 underpayment interest rates against the latest IRS figures.
Sources
Where the numbers come from
- IRS Publication 505: Tax Withholding and Estimated Tax (2026)
- IRS Form 1040-ES: Estimated Tax for Individuals (2026)
- IRS Form 2210: Underpayment of Estimated Tax by Individuals (2025 instructions)
- IRC §6654: Failure to pay estimated income tax
- IRS Quarterly Interest Rates (2026)
- IRS Estimated Taxes page