If you’re a contractor, tradesperson, or any self-employed business owner who expects to owe $1,000 or more in federal taxes for the year, you’re required to make estimated quarterly tax payments. There’s no employer withholding taxes from your pay, so the IRS expects you to pay as you earn throughout the year instead of settling up in one lump sum at filing time.

This applies to sole proprietors, single-member LLC owners, partners, and S-corp shareholders. If you’re an S-corp owner taking a W-2 salary, your payroll withholding might cover some of your tax liability. But if you also receive K-1 distributions or your withholding falls short, you’ll still need to make estimated payments on the difference.

California adds another layer. If you expect to owe $500 or more in state taxes, the Franchise Tax Board requires estimated payments too. The due dates are close to the federal schedule but not always identical, so you need to track both.

Federal estimated payments are due four times a year: April 15, June 15, September 15, and January 15 of the following year. Miss one or underpay, and the IRS charges a penalty that essentially works like interest on what you should have sent in.

There are two safe harbor methods that keep you penalty-free. You can pay 100% of what you owed last year, divided into four equal payments. Or you can pay 90% of what you’ll owe this year. If your adjusted gross income was over $150,000 last year, the safe harbor requires 110% of last year’s tax instead of 100%. Most trade business owners find it easier to base payments on prior year numbers since that figure is already known.

The biggest problem I see is business owners who have a strong year and never adjust their payments. You made $90,000 last year and are tracking toward $160,000 this year, but you’re still sending quarterly payments based on last year’s income. Come April, you’re looking at a five-figure tax bill on top of penalties. Having a tax strategy in place helps you anticipate these situations and plan for them before they become painful.

This is also where accurate books make a real difference. If you don’t know what you’re actually earning throughout the year, you can’t estimate your taxes with any accuracy. Our contractor bookkeeping services tie directly into tax planning so your estimated payments reflect your real income, not a guess from last year.

If you’ve been self-employed for a while and have never made estimated payments, you’ve likely been paying underpayment penalties every year without realizing it. Starting now with four manageable quarterly payments is far better than scrambling to cover one massive bill every April.