Quarterly Estimated Taxes: What They Are, Who Owes Them, and How to Calculate Yours

One of the more unpleasant surprises in the tax world is opening your return in April and discovering you owe a large balance — plus a penalty on top of it. For W-2 employees, withholding handles this largely automatically. But if you have income outside of a traditional paycheck, you’re generally responsible for paying your taxes throughout the year yourself.

That’s what quarterly estimated payments are for.

This guide covers everything you need to know: who has to make them, how to calculate the right amount, when they’re due, and how to avoid the underpayment penalty.

The Pay-As-You-Go System

The U.S. income tax system operates on a pay-as-you-go basis. The IRS expects taxes to be paid throughout the year as income is earned, not all at once in April. For employees, employers handle this through payroll withholding. For everyone else — freelancers, the self-employed, business owners, landlords, investors — the mechanism is quarterly estimated tax payments.

Think of estimated payments as your substitute for withholding. Instead of your employer sending a portion of each paycheck to the IRS, you send payments directly four times a year.

Who Has to Make Estimated Payments

You generally need to make quarterly estimated payments if you expect to owe at least $1,000 in federal income tax after subtracting any withholding and refundable credits — and your withholding will cover less than the smaller of:

• 90% of your current year tax liability, or
• 100% of your prior year tax liability (110% if your prior year AGI exceeded $150,000)

The second threshold is the “safe harbor” — more on that in a moment.

In practice, this affects:

• Self-employed individuals and freelancers — no employer withholding, so 100% of your tax burden falls on you
• Business owners — same situation; profits pass through to your personal return without withholding
• Investors with significant capital gains, dividends, or interest income
• Landlords — rental income arrives without withholding
• W-2 employees with significant side income — withholding may not be enough if you’re also freelancing or running a side business
• Retirees with pension, investment, or Social Security income — depending on your withholding elections, you may fall short

If you received a surprise balance due this past April and had income without withholding, estimated payments are how you prevent it from happening again.

The Four Quarterly Deadlines

“Quarterly” is a bit of a misnomer — the payment periods aren’t equal quarters. The four deadlines for 2026 are:

Notice that Q2 is only two months long (April and May) while Q3 is three months. This is a quirk of how the IRS set up the schedule — one worth knowing so you don’t underpay during the shorter periods.

The April 15 Q1 payment is due right now. If you’ve been earning self-employment or other non-withheld income since January 1, that’s the payment deadline.

How to Calculate What You Owe

There are two main methods for calculating estimated payments. You don’t have to pick just one — you can use whichever works best for your situation.

Method 1: The Safe Harbor (Prior Year Tax)

This is the simplest and most common approach. You calculate your estimated payments based on what you actually owed last year, not what you think you’ll owe this year.

• If your prior year AGI was $150,000 or less: Pay 100% of last year’s total tax liability, spread across four payments
• If your prior year AGI exceeded $150,000: Pay 110% of last year’s total tax liability

Find last year’s total tax on Form 1040, Line 24. Divide by four. Pay that amount each quarter.

Why is this called a safe harbor? Because if you pay this amount, you avoid the underpayment penalty — even if you end up owing significantly more when you file. You’ll still owe the balance in April, but no penalty.

Example: Your 2025 total tax (Form 1040, Line 24) was $12,000 and your AGI was under $150,000. Your safe harbor payment is $3,000 per quarter ($12,000 ÷ 4). Pay that amount four times and you’re penalty-free regardless of what 2026 looks like.

This approach works well when your income is relatively stable year-over-year. If you had an unusually high income year, basing 2026 payments on 2025 may mean you overpay — but that becomes a refund.

Method 2: 90% of Current Year Tax

If you expect your income to be significantly lower this year than last, or if you’re in your first year of self-employment with no prior year tax to base payments on, you can instead pay 90% of your estimated current year liability.

This requires you to estimate what you’ll actually earn and owe for 2026, which is inherently less certain. If you underestimate, you could end up with a penalty even if you made payments each quarter.

The calculation:

1. Estimate your total 2026 net income (after business expenses)
2. Calculate your self-employment tax on that income (net self-employment income × 92.35% × 15.3%)
3. Deduct the above-the-line deduction for half of SE tax
4. Apply your income tax brackets to the remaining taxable income
5. Subtract any credits you expect to claim
6. Pay 90% of that total across four payments

Most people find the safe harbor approach simpler and lower-risk. The 90% method makes sense when your income drops substantially and you want to avoid overpaying.

Form 1040-ES

Estimated payments use Form 1040-ES, which includes a worksheet for estimating your liability and four payment vouchers (one per quarter). You can download it from IRS.gov, but you don’t actually need to file the form — it’s just a worksheet and a payment coupon. The IRS tracks your payments against your account.

How to Pay

You have several options for making estimated payments:

IRS Direct Pay — Free, direct from your bank account, available at IRS.gov/payments. No account setup required. This is what I recommend for most people.

EFTPS (Electronic Federal Tax Payment System) — Free government service, requires a one-time enrollment. Good option if you want to schedule payments in advance or if you’re a business making regular deposits.

Credit or debit card — Available through third-party processors; a convenience fee applies (around 1.85–1.99% for credit). Generally not worth it unless you’re earning rewards that exceed the fee.

Mail a check — Use the Form 1040-ES voucher, make the check payable to “United States Treasury,” and note “2026 Form 1040-ES” on the memo line. Given the new USPS postmark rules and mail processing in general these days, mail early or go inside the post office for a manual postmark if mailing close to the deadline. Certified mail can help make sure it arrived as well.

Minnesota Estimated Payments

If you’re subject to Minnesota income tax, you need to make state estimated payments separately — the IRS doesn’t forward anything to Minnesota.

Minnesota estimated payments are due on the same dates as federal (April 15, June 15, September 15, January 15). Use Form M14 and pay through Minnesota’s online portal at revenue.state.mn.us.

The same general threshold applies: you need to make Minnesota estimated payments if you expect to owe more than $500 in state tax and your withholding covers less than 90% of your current year liability or 100% of last year’s.

Avoiding the Underpayment Penalty

If you don’t make adequate estimated payments, the IRS charges an underpayment penalty calculated on Form 2210. Here’s the simplest way I’ve found to explain why it exists: the IRS operates on the assumption that you’ll be paying taxes throughout the year as you earn income. When you hold onto that money instead — even unintentionally — they charge a penalty to recoup the interest they expected to earn on it.

And unlike a high-yield savings account, where you might be earning 4–5% right now, the IRS charges the federal short-term rate plus 3 percentage points, which has been running in the 7–8% range. You’re not coming out ahead by hanging onto money you owe the IRS.

The penalty isn’t a fixed dollar amount — it’s calculated on the amount underpaid for each quarter. That last part matters: the penalty is assessed separately for each payment period, which is why making payments on time throughout the year matters more than just having the right total by April. You can underpay in Q1 and Q2 and overpay in Q3 and Q4 — the early quarters still accrue a penalty even if you’re square by year-end.

The three safe harbors that eliminate the penalty:

1. You owe less than $1,000 after withholding and payments
2. Your withholding and payments cover 90% of your current year liability
3. Your withholding and payments cover 100% (or 110% if prior year AGI > $150K) of your prior year liability

Meet any one of these and there’s no penalty, regardless of what you owe in April.

What If Your Income Is Uneven?

Many self-employed people and business owners don’t earn income evenly across the year. A consultant who lands a major contract in October has most of their income in Q4, not Q1.

For situations like this, the annualized income installment method (Form 2210, Schedule AI) calculates each quarter’s payment based on what you actually earned through that point in the year — rather than assuming equal quarters. If you legitimately earned little income in Q1 but a lot in Q4, this method can reduce or eliminate the underpayment penalty for the earlier quarters.

This is more complex to calculate, but it can save real money. If your income is seasonal or lumpy, it’s worth discussing with your tax advisor.

An Alternative: Adjusting Your W-4

If you’re a W-2 employee with side income — freelance work, a small business, rental income, investment gains — you don’t necessarily have to make estimated payments. Another option is increasing your withholding from your regular paycheck.

On Form W-4 (line 4c), you can request an additional flat dollar amount be withheld each pay period. If you can estimate your side income tax and spread it across your remaining pay periods, you may be able to cover the liability through withholding instead of separate quarterly payments. Withholding is treated as paid evenly throughout the year regardless of when it’s actually withheld, which can help with the underpayment penalty calculation.

This approach works well if you have a primary W-2 job and want to simplify. Run the numbers and see whether one W-4 adjustment covers your side income — it often does.

Your First Year in Business

If you’re newly self-employed or just started a business this year, you have no prior year tax liability to base a safe harbor calculation on. (If last year’s tax was $0 because you had no income, 100% of $0 is $0 — not helpful.)

In your first year, you’ll need to estimate your current year income and use the 90% method. The best approach: run a rough projection of your expected income and expenses, calculate the approximate tax, and divide by four. Adjust as the year goes on if your income looks different than you expected.

Missing estimated payments in your first year won’t cause your business to fail — but the underpayment penalty is real and avoidable with a reasonable estimate.

Mid-Year Adjustments

Estimated payments aren’t set in stone. If your income changes significantly mid-year — business is slower than expected, you land a big contract, you sell an asset — you can adjust your remaining payments.

The IRS doesn’t care what you paid in Q1 and Q2. Each quarter stands on its own. If you underpaid early, you can catch up in later quarters (though the early-quarter penalty may already be accumulating). If you’re running ahead of income expectations, you can reduce future payments.

Reviewing your actual income and adjusting your September 15 and January 15 payments based on how the year has gone is good practice for anyone with variable income.

The Bottom Line

Estimated payments are how the pay-as-you-go system works when there’s no employer withholding in the picture. The mechanics aren’t complicated once you understand them:

• Know your deadlines (Q1 is April 15 — coming up)
• Use the prior year safe harbor if your income is consistent
• Pay on time, because each quarter is evaluated separately
• Don’t ignore this — the penalty is avoidable and the IRS notices

If you’re not sure whether you owe a Q1 payment, how much it should be, or whether your 2025 return gives you enough information to set 2026 payments up properly, let’s talk. Getting this right at the start of the year is much easier than sorting out a penalty in April.