Estimated Tax Calculator

Quick Answer

Last updated: 14 November 2026 ·How we calculate this: IRS Form 2210 safe harbor rule and 2026 tax brackets

How This Estimated Tax Calculator Works

If you have income with no tax withheld from it, such as self-employment, freelance, rental or investment income, the IRS expects you to pay tax on it as you earn it, in four quarterly installments, instead of all at once when you file. This calculator uses the IRS “safe harbor” rule to work out how much to pay each quarter so you avoid an underpayment penalty.

How to Use the Estimated Tax Calculator

1. Choose your filing status.
2. Enter your expected income and any pre-tax contributions or deductions.
3. Enter your expected self-employment tax, if any (use the Self-Employment Tax Calculator to find it).
4. Enter tax already withheld this year, and last year’s tax and AGI if you know them.
5. Press Calculate to see your required annual payment and quarterly amount.

How the Required Payment Is Calculated

• Taxable income: expected income − pre-tax contributions − the larger of the standard deduction and itemized deductions
• This year’s expected tax: income tax on that taxable income + expected self-employment tax − credits
• Test A: 90% of this year’s expected tax
• Test B (only if you enter last year’s figures): 100% of last year’s tax, or 110% if last year’s AGI was over the threshold
• Required annual payment: the smaller of Test A and Test B (or just Test A if you skip last year’s figures)
• Quarterly payment: (required annual payment − tax already withheld) ÷ 4

Key Terms

• Safe harbor: a rule that protects you from a penalty if you pay at least a set minimum, even if you end up owing more.
• Adjusted gross income (AGI): your total income minus certain adjustments, before deductions.
• Underpayment penalty: an IRS charge for not paying enough tax during the year, even if you pay the full balance when you file.
• Self-employment tax: the Social Security and Medicare tax self-employed people pay instead of payroll withholding.

Worked Example

A single filer expects $90,000 of income this year, with $5,000 going into a 401(k) and about $11,000 of self-employment tax. Nothing is withheld. Last year their tax was $14,000 on an $85,000 AGI.

• Taxable income = $68,900; income tax on that = $9,870.00
• This year’s expected tax (income tax + self-employment tax) = $20,870.00
• 90% of this year’s tax = $18,783.00; 100% of last year’s tax = $14,000 (AGI was under $150,000, so no 110%)
• Required annual payment = the smaller of the two = $14,000.00
• Quarterly payment = $14,000.00 ÷ 4 = $3,500.00

Real-Life Examples

• Self-employed, $90,000 income: with $11,000 of self-employment tax and no withholding, the quarterly payment is about $3,500.
• Married couple, $220,000 income: with $18,000 withheld from a job and last year’s AGI over $150,000, the higher-income 110% rule applies and the quarterly payment is about $1,000.
• Small side income, $30,000: with $2,600 already withheld from a main job, the required payment comes out to about $0 a quarter (or the de minimis rule may apply).
• Skipping last year’s figures: using only the 90% test on the first example alone gives the same $18,783 required payment, since it was already the smaller of the two tests.

Estimated Tax vs Withholding

• Withholding: your employer takes tax out of each paycheck automatically and sends it to the IRS.
• Estimated tax: you calculate and send in the tax yourself, usually because income such as self-employment, freelance or investment earnings has no withholding.
• You can use both: increasing withholding from a job is another way to cover tax owed on side income, instead of making separate quarterly payments.

Estimated Tax Due Dates (2026)

IRS Form 1040-ES; a due date that falls on a weekend or holiday moves to the next business day.

Why the 110% Rule Exists, and Who It Affects

The 110%-of-last-year rule only kicks in for higher earners: if your adjusted gross income last year was over $150,000 (or $75,000 if you file separately this year), the IRS raises the prior-year test from 100% to 110%, so you cannot lean on a low prior-year bill to avoid paying enough this year. Most filers below that threshold can simply pay 100% of last year’s tax, split into four payments, and know for certain they will not owe a penalty even if this year’s income is much higher. If you skip entering last year’s figures, the calculator uses only the 90%-of-this-year test, which is always a valid safe harbor on its own but requires a good estimate of this year’s income.

Common Mistakes to Avoid

• Forgetting self-employment tax. It is often larger than the income tax on the same earnings.
• Using last year’s AGI threshold for the wrong year. The $150,000 test uses last year’s AGI, not this year’s.
• Skipping estimated payments because a refund came last year. A refund does not guarantee this year’s withholding and payments are enough.
• Paying the full year’s estimate in one lump sum late in the year. The IRS generally expects roughly even quarterly payments, not one large payment at the end.
• Ignoring the $1,000 de minimis rule. If you will owe under $1,000 after withholding, you may not need to pay estimated tax at all.

Frequently Asked Questions

References & Sources