What are the 2026 quarterly estimated tax deadlines?

Q1 (income January through March): April 15, 2026. Q2 (income April through May): June 16, 2026 (Monday). Q3 (income June through August): September 15, 2026. Q4 (income September through December): January 15, 2027. Note that Q2 covers only two months, not three -- a common source of confusion.

What is the current IRS underpayment interest rate?

The IRS underpayment rate for 2026 is the federal short-term rate plus 3 percentage points, adjusted quarterly. Recent rates have been in the 7% to 8% range. Interest accrues daily on the underpayment amount from the payment due date through the date of payment or filing, whichever is earlier.

Can I pay all four quarters at once in January?

No. Estimated taxes must be paid in four separate installments throughout the year. Paying the full annual amount in January does not satisfy Q1, Q2, and Q3 obligations -- those quarters accrue underpayment interest from their respective due dates.

What form do I use to pay quarterly estimated taxes?

IRS Form 1040-ES (Estimated Tax for Individuals). Most taxpayers pay online through IRS Direct Pay (free) at irs.gov/payments or by mailing Form 1040-ES payment vouchers. Payment is applied to the quarter in which it is received, so mail at least five business days before the deadline.

Tax & Payroll

Quarterly Estimated Tax Calculator

Calculate quarterly estimated tax payments with safe harbor amounts and 2026 IRS deadlines.

Income Projection

Expected Annual Income ($)

Business Expenses ($)

W-2 Withholdings / Credits ($)

Prior Year Total Tax ($)

Used for 110% safe harbor calculation.

Quarterly Estimates

Enter your income projection and click calculate.

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Introduction

The IRS charged $1.6 billion in underpayment penalties in fiscal year 2023, and most of it fell on self-employed workers and freelancers who did not make quarterly estimated payments -- or made them too small. The rule is straightforward but often misunderstood: if you expect to owe $1,000 or more in federal tax for the year, you must pay in four installments throughout the year, not one lump sum in April. Miss the deadlines or underpay, and the IRS charges interest on the shortfall from the date each payment was due -- currently at 8% annually per the IRS underpayment rate table. This calculator uses the IRS safe harbor method (110% of prior year tax for those with AGI above $150,000) alongside your current year projection to determine the minimum payment amount that protects you from penalties each quarter.

What This Calculator Does

This quarterly estimated tax calculator computes safe, penalty-free payment amounts for self-employed individuals, freelancers, independent contractors, and investors with unwithheld income. Enter your projected annual net income, prior year total tax (from Form 1040, line 24), and any W-2 withholding. The calculator applies both the 90% current-year method and the 100%/110% prior year safe harbor to determine which produces the lower minimum payment, displays all four payment dates, and shows the quarterly payment needed under each method.

The Formula

Safe Payment = Max(90% of Current Year Tax / 4, Prior Year Safe Harbor / 4) -- Withholding / 4 | Prior Year Safe Harbor = 100% of Prior Year Tax (or 110% if prior year AGI > $150,000)

The IRS offers two methods for avoiding underpayment penalties. Method 1: pay at least 90% of your current year actual tax liability in four equal installments. Method 2: pay at least 100% of last year's total tax (110% if last year's AGI exceeded $150,000) spread across four payments. You qualify for the safe harbor under whichever method produces the lower total payment. W-2 withholding from any employer counts toward your annual payment requirement, reducing the amount needed via quarterly estimates. The calculator takes the conservative approach by recommending the higher of the two methods to eliminate any penalty risk.

Step-by-Step Example

Gather prior year tax information

From your prior year Form 1040: Line 11 (AGI): $142,000. Line 24 (Total Tax): $28,400. Since AGI is below $150,000, the safe harbor is 100% -- total $28,400, or $7,100 per quarter.

Project current year income and tax

Projected net 1099 income: $155,000. Estimated SE tax: $21,900. Estimated federal income tax after deductions: $24,800. Total projected tax: $46,700. 90% of current year: $42,030, or $10,508 per quarter.

Account for any W-2 withholding

Spouse's W-2 annual withholding: $8,400. Annual withholding credit: $8,400. Reduced quarterly obligation: ($42,030 - $8,400) / 4 = $8,408 per quarter using current-year method.

Select payment amount and set reminders

Current-year method: $8,408/quarter. Prior-year safe harbor: ($28,400 - $8,400) / 4 = $5,000/quarter. Pay the higher amount ($8,408) to stay protected under both methods. Set calendar reminders for April 15, June 15, September 15, January 15.

Real-World Use Cases

Volatile Income Freelancer

A freelance consultant with unpredictable income uses the prior year safe harbor method exclusively. If last year's total tax was $32,000 and AGI was $180,000, they pay $32,000 x 110% / 4 = $8,800 per quarter regardless of current year revenue fluctuations -- completely eliminating penalty risk.

New Freelancer in First Year

A first-year freelancer with no prior year 1099 income cannot use the safe harbor method since there is no prior year SE tax. They project their annual income, calculate total tax, and pay 25% each quarter using the 90% current-year method. A mid-year income spike requires recalculating and adjusting Q3 and Q4 payments.

Dual-Income Household

A household where one spouse earns W-2 income ($95,000, withholding $14,200) and the other earns 1099 income ($80,000) calculates the 1099 spouse's total tax liability, subtracts the W-2 spouse's withholding, and divides the remainder by four. Often the W-2 withholding covers a significant portion of the combined household tax, reducing quarterly payment amounts.

Comparison

Method	Calculation	Benefit	Best For
90% Current Year	90% of projected current year tax / 4	Lower payments if income drops	Predictable income, accurate projections
100% Prior Year (AGI ≤ $150K)	100% of last year's tax / 4	No penalty regardless of current year	Any income level with prior year tax history
110% Prior Year (AGI > $150K)	110% of last year's tax / 4	Complete penalty protection for high earners	Self-employed with AGI above $150,000
Annualized Income Method	Calculated on Form 2210 AI Schedule	Avoids overpaying in low-income quarters	Highly seasonal or uneven income patterns

Common Mistakes to Avoid

Missing quarterly deadlines. The IRS charges interest on underpayments from the due date of each quarter -- not just at year end. Q1 missed by one day still accrues underpayment interest for that entire quarter.
Using last year's safe harbor without checking the $150,000 AGI threshold. If your prior year AGI exceeded $150,000, the safe harbor requires 110% of prior year tax, not 100%. Using 100% triggers a penalty.
Forgetting to subtract W-2 withholding before dividing by four. A household with $10,000 in W-2 withholding does not need to pay quarterly estimates on that $10,000 -- it is already paid in.
Not adjusting mid-year when income significantly changes. If you land a large contract in Q2 that doubles your projected income, recalculate and increase Q3 and Q4 payments to stay within the 90% current-year threshold.

Frequently Asked Questions

Accuracy and Disclaimer

Quarterly tax estimates are based on your projected income and 2026 IRS rates. Actual tax obligations depend on final income, deductions, credits, filing status, and state tax requirements. The safe harbor calculations shown use projected 2026 federal thresholds. The IRS underpayment penalty rate is subject to quarterly adjustment. Consult a licensed CPA or enrolled agent for personalized estimated payment planning.

Conclusion

Quarterly estimated tax payments are the foundation of responsible self-employment cash management. Underpaying costs you interest penalties; overpaying locks up cash you could use in the business. Once you have your quarterly amounts set, use the Self-Employment Tax Calculator to verify your annual SE tax burden, and the Take-Home Pay Calculator to model how different income levels affect your total after-tax income.