Quarterly Estimated Taxes for the Self-Employed: The Cash-Flow System That Stops April From Wrecking You

Quarterly estimated taxes for self-employed people are four payments a year that cover the income tax and self-employment tax nobody withholds from your paycheck. You generally have to make them if you expect to owe at least $1,000 for the year after withholding and credits. For 2026, the IRS due dates are April 15, June 15, and September 15, 2026, plus January 15, 2027.

The rules are simple. The problem is cash. Most founders don’t get hurt by the tax itself. They get hurt because the money they owe the IRS was sitting in the same account as the money they spent.

Why April Wrecks So Many Founders

Picture a freelance designer in her first full year on her own. Clients pay on time, the business account looks healthy, and every month she thinks, “I’m doing well.” She is. She’s also spending money that was never fully hers.

When she sits down to file, she finds out she owes a five-figure balance, plus a penalty for not paying during the year. Nothing went wrong with her business. Something went wrong with her system. She didn’t have one.

When you work for someone else, an employer quietly takes tax out of every paycheck. When you work for yourself, you become the payroll department. If you don’t build the withholding, nobody will.

Do You Actually Have to Pay Estimated Taxes?

According to the IRS Form 1040-ES instructions for 2026, you generally must pay estimated tax if both of these are true:

1. You expect to owe at least $1,000 in tax for 2026 after subtracting withholding and refundable credits.
2. You expect your withholding and refundable credits to be less than the smaller of 90% of your 2026 tax or 100% of the tax shown on your 2025 return (if that return covered all 12 months).

There’s one clean exception. If you were a U.S. citizen or resident for all of 2025 and had zero tax liability for that full year, you don’t have to pay estimated tax for 2026.

For most profitable solo founders, freelancers, and consultants, the answer is yes. If you have a side business on top of a W-2 job, you may be able to cover it by raising your withholding at work instead.

The 2026 Due Dates

The “quarters” aren’t actually equal. The second period is two months, and the last one is four. That’s why budgeting by calendar quarter catches people off guard.

A few details from the IRS worth knowing:

• If a due date lands on a Saturday, Sunday, or legal holiday, the next business day counts. None of the 2026 dates above fall on a weekend.
• You can skip the January 15, 2027 payment if you file your 2026 return by February 1, 2027 and pay the full balance with it.
• You can make more than four payments. Paying monthly is fine as long as each period’s total is covered by its due date.
• If you mail a check, the IRS now warns that the postmark is the date USPS processes it, which may not be the day you drop it off. Paying online through IRS.gov/payments removes that risk.

How to Calculate What You Owe

Your estimated tax has two parts: income tax and self-employment tax. The second one is what surprises new founders.

Self-employment tax is your Social Security and Medicare, both halves of it, because you’re the employee and the employer. The 2026 Form 1040-ES worksheet works it out like this:

1. Take your expected net profit and multiply by 92.35%.
2. Multiply that by 2.9% for Medicare.
3. Multiply the same amount (up to the 2026 Social Security wage base of $184,500, minus any W-2 wages) by 12.4% for Social Security.
4. Add them together. Half of that total is deductible when you figure your income.

Say you expect $80,000 of net profit. That’s $73,880 after the 92.35% step, which puts your self-employment tax at roughly $11,300 before a dollar of income tax. Income tax then gets figured on top of that using your brackets and deductions, which is where the full Form 1040-ES worksheet, or your CPA, comes in.

The Safe Harbor That Takes the Guesswork Out

Here’s the rule I’d build my whole system around. You generally avoid the underpayment penalty if you pay, on time and in equal installments, the smaller of:

• 90% of this year’s tax, or
• 100% of last year’s total tax.

If your 2025 adjusted gross income was more than $150,000 ($75,000 if you’re married filing separately for 2026), that second number becomes 110%.

Why it matters: you don’t know this year’s income yet, but you do know last year’s tax. Say your 2025 return showed $18,000 of total tax and your AGI was under $150,000. Pay $4,500 by each due date and you’ve generally covered the penalty side, even if 2026 turns out bigger. You’ll still owe the difference in April, but you won’t be fined for it.

If your income is lumpy, say most of it lands in the fourth quarter, IRS Publication 505 explains the annualized income installment method. It lets your payments follow your income instead of four equal amounts, and you file Form 2210 with Schedule AI to show it.

The Tax Bucket System: 5 Steps

The rules tell you what to pay. This is how I’d make sure the money is actually there.

1. Open a separate tax account. A plain savings account at a different bank works well. If you can’t see it every day, you won’t spend it.
2. Skim every deposit. Move a fixed percentage of every client payment into the tax account the day it lands. Ask your CPA to set the percentage from last year’s return. A common starting buffer is 25% to 30%, adjusted once your CPA runs the real numbers.
3. Put the four dates on your calendar now. Add a reminder two weeks before each one. Pay from the tax account, never the operating account.
4. Check in after each payment. Compare your year-to-date profit to your plan. If income jumped, raise the next payment. If it dropped, talk to your CPA before you cut it.
5. Keep the surplus in the bucket. If the account has more than you need in April, that’s your cushion, not a bonus.

This only works if your personal pay comes out of what’s left, not out of the tax money. If you haven’t set that up yet, decide how to pay yourself before you decide what you can afford. And if the skim feels painful, the cash flow habits that keep a solo founder steady through slow months make it easier to stick with.

What Happens If You Miss a Payment

The IRS charges the penalty on each underpayment for the number of days it stays unpaid. You can owe it even if you end up getting a refund when you file, because it’s about timing, not just the total.

If you’re behind right now, the fix is to pay as soon as you can. Every day you wait adds to the penalty, and the IRS may waive it in certain situations explained in the Form 2210 instructions. A missed quarter is a cash-flow problem, not a character flaw. Fix the system and move on.

The Real Lesson

Estimated taxes aren’t a punishment for working for yourself. They’re the price of keeping the whole paycheck in your hands. The founders who stay calm in April aren’t the ones with the lowest tax bill. They’re the ones who stopped treating the IRS’s share as their money.

Build the bucket. Feed it every time you get paid. Put the dates in your calendar. Then let a CPA tighten the numbers.

This article is for education only and is not tax advice. Your situation may differ, so work with a qualified CPA or tax professional before setting your payment amounts.

Frequently Asked Questions

Do I have to pay estimated taxes in my first year of self-employment?

Usually, if you expect to owe at least $1,000. The exception: if you were a U.S. citizen or resident all of last year with zero tax liability for that full 12-month year, you don’t have to pay estimated tax.

Is self-employment tax included in quarterly estimated payments?

Yes. Your estimated payments cover both income tax and self-employment tax together. The Form 1040-ES worksheet figures self-employment tax on 92.35% of your net profit, and half of that tax is deductible when figuring your income.

Can I pay all my estimated taxes at once?

Yes. The IRS lets you pay your full 2026 estimated tax by April 15, 2026. You can also pay more often than four times, as long as each period’s required amount is paid by its due date.

Can I skip the January 15 estimated tax payment?

You can if you file your 2026 return by February 1, 2027 and pay the entire balance due with it. For most founders, waiting on year-end paperwork makes that tight, so plan on the January payment.

What if my income changes a lot during the year?

Refigure your estimate and adjust the remaining payments. If income arrives unevenly, IRS Publication 505 explains the annualized income installment method, which matches payments to when you earn the money. Form 2210 with Schedule AI supports it.