Who has to pay estimated taxes?

Generally anyone who expects to owe at least $1,000 in tax after subtracting withholding and refundable credits. In practice that means most self-employed people, landlords, partners receiving K-1 income, and W-2 employees with substantial investment income that is not covered by payroll withholding.

When are estimated tax payments due?

Four times a year, on roughly April 15, June 15, September 15, and January 15 of the following year. The quarters are not equal in length despite the name. When a due date falls on a weekend or holiday the deadline shifts to the next business day.

What is the estimated tax safe harbor?

You avoid the underpayment penalty if you pay at least 90 percent of the current year tax or 100 percent of the prior year tax, whichever is smaller. If your prior year adjusted gross income exceeded $150,000, the prior year threshold rises to 110 percent. Meeting a safe harbor prevents the penalty even if you still owe a large balance.

Can I use withholding instead of estimated payments?

Yes, and it is often better. Withholding is treated as paid evenly across the year regardless of when it was actually withheld, so increasing withholding late in the year can retroactively cure earlier underpayment. An estimated payment is credited only to the quarter in which it was made.

What happens if I skip an estimated tax payment?

The IRS charges an underpayment penalty calculated quarter by quarter at an interest rate that adjusts periodically. It is not a flat fee, and paying the full balance in April does not erase penalties that accrued on earlier quarters. Missing one quarter and doubling up later does not fix it.

IRS Form Guide

Form 1040-ES

The quarterly payment system for income nobody withholds from, and the safe harbor that makes the penalty avoidable even in a great year.

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A guide by Taxstra Tax & Accounting · CPA-led tax strategy for business owners

Your Guide

01Who Actually Owes Estimated Tax 02The Four Due Dates 03The Safe Harbor 04The Withholding Trick 05Frequently Asked Questions

IRS Form Guides>Form 1040-ES

Written by Bryan Martin, CPA, Managing Partner and Founder of Taxstra. Last updated August 15, 2026.

Quick answer

Form 1040-ES is used to calculate and pay estimated tax on income without withholding, such as self-employment, rental, and investment income. Payments are due four times a year. Paying 100 percent of last year's tax, or 110 percent if prior year AGI exceeded $150,000, avoids the underpayment penalty.

The U.S. tax system is pay as you go. A W-2 employee satisfies that automatically through payroll withholding. Everyone else has to do it manually, four times a year, and Form 1040-ES is the mechanism.

The form is unusual in that you never file it. The worksheet is for your own calculation and the vouchers exist only if you pay by mail. What matters is that the money arrives on time.

Who Actually Owes Estimated Tax

Broader than just the self-employed.

The trigger is expecting to owe at least $1,000 after withholding and refundable credits. That threshold catches a lot of people who do not think of themselves as self-employed.

Self-employed and 1099 contractors

Income tax plus self-employment tax, with nothing withheld from either.

Landlords and real estate investors

Rental profit carries no withholding, and depreciation recapture on a sale can create a large single-quarter obligation.

Partners and S corporation shareholders

K-1 income is taxable whether or not it was distributed, which is why partners can owe tax on money they never received.

W-2 employees with large investment income

Payroll withholding is calculated on wages only. A large realized gain or a Roth conversion is not covered by it.

Retirees taking distributions

Withholding on retirement distributions is elective and often set too low or declined outright.

The first year trap

Someone who leaves a W-2 job in January for 1099 work often makes no estimated payments at all, reasoning that they will settle up in April. By April they owe a full year of income tax, a full year of self-employment tax, and an underpayment penalty on all four quarters.

The Four Due Dates

The quarters are not actually quarters.

Payment	Income period covered	Approximate due date
First	January 1 to March 31	April 15
Second	April 1 to May 31	June 15
Third	June 1 to August 31	September 15
Fourth	September 1 to December 31	January 15 of the following year

Watch Out

The second quarter is two months long

The second payment covers April and May only, then is due on June 15. People who budget in even thirds across a three month window routinely underpay this one. Deadlines that land on a weekend or federal holiday move to the next business day.

The Safe Harbor

Pay this much and the penalty cannot apply, whatever you end up owing.

The underpayment penalty is not about owing money in April. It is about whether you paid enough during the year. The safe harbor gives you a fixed target that removes the guesswork.

Prior year AGI at or below $150,000

Pay 100 percent of last year's total tax, or 90 percent of this year's, whichever is less. Last year's number is already known, which makes it the practical target.

Prior year AGI above $150,000

The prior year threshold rises to 110 percent of last year's total tax. The 90 percent current year option still applies, but it requires forecasting a year that is not finished.

Taxstra CPA Tip

Taxstra Tip

In a year when income jumps sharply, the prior year safe harbor is enormously valuable. You can legally pay based on a much smaller prior year liability, keep the difference invested until April, and owe no penalty. The tax still comes due, but the timing is yours.

The mechanics of how the penalty is computed when a safe harbor is missed, including the annualized income method for uneven earnings, are covered in the estimated tax penalty guide, and you can size it with the penalty calculator.

The Withholding Trick

The one legitimate way to fix a quarter you already missed.

Estimated payments are credited to the quarter in which they are made. Withholding is different: it is treated as paid evenly throughout the year no matter when it was actually withheld. That asymmetry is genuinely useful.

How it works in practice

You realize in November that you underpaid the first three quarters by $12,000 in total.

Paying $12,000 as a Q4 estimate

Credited entirely to the fourth quarter. Q1 through Q3 remain underpaid and the penalty still accrues on them.

Withholding $12,000 from a year-end paycheck or distribution

Treated as $3,000 paid in each quarter. The earlier underpayment is retroactively cured.

Illustrative only. Requires a wage or distribution source you can actually withhold from.

The two usual sources are a spouse's W-2, adjusted via a new Form W-4, and a year-end retirement distribution with a large voluntary withholding election. Neither is available to everyone, which is why the practical routine in the quarterly estimated taxes guide remains the better default. Self-employed filers should size the obligation using the self-employment tax guide and reduce the base with the 1099 deduction checklist. Physicians with locum or moonlighting income should see the physician estimated tax guide, agents should see the real estate agent version, and Californians need the state schedule, which does not match the federal one.

First Year With 1099 or K-1 Income?

The most common first-year mistake is setting aside for income tax and forgetting self-employment tax entirely. A Taxstra CPA will size it correctly. The initial consultation is free.

Frequently Asked Questions

Form 1040-ES is the worksheet and voucher package used to calculate and pay estimated tax on income that has no withholding. Self-employment income, rental income, investment gains, and K-1 distributions all typically require it. The form itself is never filed with the IRS; only the payment is submitted.

Estimated Payments Are Cash Flow, Not Strategy

Paying the right amount on time avoids penalties. Changing what you owe in the first place requires entity and retirement planning. Book a free initial consultation.

Next Steps

Filing it yourself is fine. Optimizing it is where the money is.

Getting the form right keeps you out of trouble. The strategies below are what actually lower the bill.

Want a CPA to run the numbers for you?

Free 30-minute call with a Taxstra CPA. No pressure, just the math for your situation.

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Authoritative Sources

Citations reflect U.S. federal tax law as of the article's last reviewed date.

Related Estimated Tax Guides

Quarterly Estimated Taxes

The practical system for setting money aside and paying on schedule.

The Estimated Tax Penalty

How the penalty is computed quarter by quarter, and how to unwind it.

California Estimated Payments

California uses a completely different quarterly split from the federal schedule.

1099 Tax Deductions

Lowering the number your estimates are based on.