Quarterly Estimated Tax Calculator

Quarterly Estimated Tax Calculator

How to Use the Quarterly Estimated Tax Calculator

1. 1

   Enter this year's income

   Choose your filing status, then type your expected net self-employment profit for 2026 and any other income. Leave the W-2 switch on if the other income is wages.

2. 2

   Add expected withholding

   Enter the federal income tax you expect to have withheld from paychecks or pensions this year. Withholding counts toward the required payment.

3. 3

   Enter last year's tax and AGI

   From your 2025 Form 1040, enter the total tax and your adjusted gross income. These unlock the prior-year safe harbor, which is often the smaller target.

4. 4

   Read your installments

   The calculator shows the safe-harbor amount per quarter with its due date, marks dates that have already passed, and shows how much to pay to avoid a bill in April.

How estimated tax payments work

The US tax system is pay-as-you-go. Employees pay through withholding; if you are self-employed, you usually pay during the year with estimated tax payments on Form 1040-ES. Those payments cover both your income tax and your self-employment tax.

You generally must make estimated payments if you expect to owe $1,000 or more when you file, after withholding and refundable credits. To avoid the underpayment penalty, your withholding plus timely estimated payments must reach the required annual payment, which is the smaller of two safe harbors: 90% of this year's tax, or 100% of last year's tax. If last year's AGI was over $150,000, the prior-year figure rises to 110%. The prior-year safe harbor needs a return that covered a full 12 months.

The required amount is split into four equal installments. Withholding is treated as paid evenly through the year, no matter when it was actually taken out of your pay.

Projected tax = income tax + self-employment tax (+ Additional Medicare Tax)
Required annual payment = lesser of (90% × projected tax) or (100% × last year's tax; 110% if last year's AGI > $150,000)
Each installment = (required annual payment − withholding) ÷ 4

2026 estimated tax due dates

The four payment periods are not equal quarters. If a due date falls on a weekend or legal holiday, it moves to the next business day.

Worked examples: using the safe harbor

A single filer expects $90,000 of self-employment profit in 2026 and has no other income or withholding. Their 2025 return showed total tax of $15,000 and AGI of $80,000.

• Self-employment tax: $90,000 × 92.35% × 15.3% = $12,717. Half of it, $6,358, is deductible, so AGI is $83,642.
• Minus the $16,100 standard deduction leaves $67,542. The 20% QBI deduction is $13,508, so taxable income is $54,033.
• Income tax: $1,240 at 10% + $4,560 at 12% + $799 at 22% = $6,599. Projected 2026 tax: $6,599 + $12,717 = $19,316.
• 90% of this year: $17,384. 100% of last year (AGI under $150,000): $15,000. The smaller is $15,000.
• Estimated payments: $15,000 ÷ 4 = $3,750 per quarter. That avoids the penalty, but about $4,316 would still be due in April. To cover the full projection instead, pay $4,829 per quarter.

The underpayment penalty and catching up

If you pay too little or too late, the IRS charges an underpayment penalty figured on Form 2210. It works like interest: it is based on the IRS underpayment rate, which is set each quarter, and runs on each missed installment from its due date until it is paid or until the filing deadline. Paying late costs less than not paying.

If you start mid-year, pay as soon as you can to stop the penalty on earlier installments, and make the next ones on time. If your income is uneven, for example most of it arrives late in the year, the annualized income installment method on Form 2210 Schedule AI can lower or remove the penalty. You can also skip the January payment if you file your return and pay everything by January 31, 2027. W-2 earners with a side business can instead raise their withholding on Form W-4, which counts as paid evenly through the year.

Legal ways to lower the tax you have to prepay

Lowering your projected tax lowers every installment. These strategies are legal and common for small businesses; keep records for each one.

• Deduct all ordinary and necessary business expenses, which reduce both income tax and self-employment tax.
• Claim the home office deduction if part of your home is used regularly and exclusively for the business.
• Buy needed equipment with Section 179 expensing (up to $2,560,000 for 2026) rather than depreciating it over years; the Section 179 calculator shows the effect.
• Fund a Solo 401(k) (up to $24,500 of employee deferrals for 2026, plus $8,000 catch-up at 50 or older, plus an employer contribution) or a SEP-IRA.
• Take the self-employed health insurance deduction and, with a high-deductible plan, contribute to an HSA ($4,400 self-only or $8,750 family for 2026).
• Pay your children under 18 a reasonable wage for real work in a sole proprietorship: the wages are deductible and exempt from Social Security and Medicare.
• Make sure the 20% QBI deduction is claimed; above the threshold, the rules get more involved and a professional can help.

Limits of this calculator

It assumes the standard deduction, even payments and ordinary income only, and it does not model credits, itemized deductions, capital gains, net investment income tax, retirement or health insurance deductions, the QBI deduction above the threshold, farmer and fisher rules, the annualized income method or state estimated tax. Married filing separately is not supported. Use it to plan, and check with a CPA or enrolled agent when the stakes are high.

Features

• Projects 2026 income tax plus self-employment tax
• Safe harbor: lesser of 90% of this year or 100%/110% of last year's tax
• Subtracts expected withholding from wages
• Four installments with 2026 due dates, flagging dates that have passed
• Shows a second amount that covers your full projected tax

Frequently Asked Questions