How do I estimate quarterly taxes for self-employment?

If you are self-employed — sole proprietor, single-member LLC, 1099 contractor, freelance — you generally have to pay federal income tax and self-employment tax four times a year, because no employer is withholding it for you. IRS Form 1040-ES is the worksheet and payment vehicle for this.

The quarterly due dates are the same every year:

• Q1: April 15 (covers Jan 1 – Mar 31)
• Q2: June 15 (covers Apr 1 – May 31)
• Q3: September 15 (covers Jun 1 – Aug 31)
• Q4: January 15 of the following year (covers Sep 1 – Dec 31)

If the 15th falls on a weekend or federal holiday, the deadline shifts to the next business day.

There are two ways to estimate each quarter, and the IRS lets you choose:

Method 1: Annualize your expected income for the year. Project your total income, deductions, and tax liability for the full year, divide by four, and pay that amount each quarter. This works well if your income is steady or you expect similar earnings each quarter. If your income is seasonal — most of your year in Q4, say — annualizing will overcharge you early and give you a large refund later, but won’t trigger a penalty.

Method 2: Use the safe-harbor rules. Pay the lower of:

• 90% of your current year’s tax liability, or
• 100% of your prior year’s tax liability (110% if your prior-year AGI was over $150,000, or $75,000 if married filing separately).

If you meet the safe-harbor threshold by year-end, you owe no underpayment penalty regardless of whether your estimates were accurate. This is the path most self-employed people should default to unless they have a very stable income. The mechanism: if you paid at least 100% (or 110%) of last year’s total tax through withholding and estimated payments combined, the IRS waives the penalty for underpayment. Withholding counts toward this — so if a spouse withholds enough through their W-2 job, you can effectively skip estimated payments entirely.

The actual math, simplified:

1. Estimate your net self-employment income (gross receipts minus business expenses).
2. Apply the self-employment tax rate (15.3% on 92.35% of net earnings, then 50% deductible against income tax).
3. Add federal income tax on the remaining income, factoring in your filing status, deductions, and credits.
4. Divide by 4. That’s your quarterly payment.

The two pitfalls that bite most often:

• Forgetting self-employment tax. Self-employment tax (Social Security + Medicare) is in addition to income tax and catches a lot of new freelancers off guard. It is roughly 15.3% of net earnings up to the Social Security wage base, plus 2.9% Medicare on the rest.
• Waiting until April to start. Each quarterly payment covers a specific three-month period. If you skip Q1 (April 15) and try to “catch up” in Q2 (June 15), the IRS charges interest on the Q1 underpayment from April 15 onward — even if you pay it in June. The penalty is small but it is per-quarter, and it compounds if you keep skipping.

A practical setup that works:

1. Open a separate bank account labeled “taxes.” Every time a client pays you, immediately transfer 25–30% of the deposit to the tax account. This is the self-employed version of “pay yourself first” — except the “yourself” here is the IRS.
2. Run the 1040-ES worksheet once per quarter when your income picture has stabilized for that period. Adjust Q2/Q3/Q4 if income is trending up or down.
3. Pay electronically via IRS Direct Pay or EFTPS (the Electronic Federal Tax Payment System). EFTPS is free and lets you schedule payments in advance, which is useful for self-employed people whose income is lumpy.
4. Don’t agonize over precision. The penalty for imperfect estimates is small — a few hundred dollars on a $5,000 underpayment is typical. The penalty for skipping entirely is bigger. Aim for accuracy within 10% of your actual liability and the IRS won’t care.

If you are also weighing whether to leave a job for self-employment, the unsubsidized health-insurance cost is the other big financial line item most people underestimate. The why-people-stay-in-jobs-for-health-insurance answer covers that side of the math — together, taxes and health benefits are the two costs that surprise most new solo founders.

Once you have a year of estimated taxes behind you, the practical next step is opening a dedicated business bank account so the 25–30% you’re setting aside for taxes actually stays set aside instead of leaking into operating expenses. The discipline is mechanical, but the discipline is the whole game.