How much should an owner operator set aside for quarterly estimated taxes?

An owner-operator often sets aside part of every settlement to cover two things: self-employment tax and income tax. Many people in this situation start with a flat percentage of net earnings (the money left after business expenses) and adjust it later with a tax professional. Figures of roughly 25 to 35 percent are sometimes discussed as a starting point. The right number depends on your income, deductions, filing status and state. Treat any percentage as a starting habit, not a final answer.

What you are setting aside for

Self-employment tax. This is the Social Security and Medicare tax that an employer and employee would normally split. When you work for yourself, you generally pay both halves. The rate is 15.3 percent: 12.4 percent for Social Security plus 2.9 percent for Medicare. It generally applies to 92.35 percent of your net earnings from self-employment, which is revenue minus allowable business expenses. The Social Security part stops at an annual wage base limit. An additional Medicare tax can apply at higher incomes. Check the IRS instructions for the current details.

Income tax. This sits on top of self-employment tax. How much you owe depends on your total taxable income, your filing status and your deductions. Your state may also charge income tax. Because these vary so much, no single percentage fits every driver.

When the payments are due

Estimated taxes are generally paid in four installments through the year. The usual dates are about:

• April 15
• June 15
• September 15
• January 15 (of the following year)

These dates can move when one falls on a weekend or holiday. The periods they cover are not equal three-month blocks. Verify each year’s dates with the IRS before you pay. Your state may have its own schedule.

A simple set-aside habit

One common method is to move a fixed percentage out of every settlement as soon as it lands, into a separate savings account used only for taxes. Doing this consistently, before spending on anything else, means the money is already there when a due date arrives.

Base the percentage on net earnings where you can. If you only look at gross settlements, you may set aside too much, since fuel, repairs, insurance and other business costs reduce what you are taxed on. Keep good records so you know your real net.

If you run interstate, remember that IFTA fuel tax reporting and any DOT-related fees are separate obligations. Keep that money out of your tax account.

Worked example

These numbers are round and made up for illustration only. They are not a prediction of your tax.

• Gross settlements for the quarter: $30,000
• Business expenses for the quarter: $12,000
• Net earnings: $18,000
• Self-employment tax: $18,000 × 92.35% × 15.3% ≈ $2,543
• Assumed income tax at a made-up blended 12 percent of net earnings (ignoring deductions): $2,160
• Total set aside: about $4,703

That is roughly 26 percent of net earnings, or about 16 percent of gross settlements. In this example, setting aside 30 percent of net earnings ($5,400) would leave a cushion of roughly $700. Your own figures will differ. Deductions can lower the real result. One example is the deduction for half of your self-employment tax, which reduces taxable income for income tax purposes. Other income in your household can raise it.

Safe harbor, in general terms

The IRS has “safe harbor” rules. Generally, you can avoid an underpayment penalty if your payments during the year reach certain targets, even if you still owe a balance at filing time. Commonly cited targets are a set share of the current year’s tax (often 90 percent) or a share of last year’s tax (often 100 percent, or 110 percent for higher-income taxpayers). Owing a small balance at filing can also avoid the penalty. Thresholds and exceptions change, so look up the current rules on the IRS website or ask a tax professional which target applies to you.

Common mistakes

• Setting aside nothing until the due date, then having no cash.
• Calculating the percentage on gross settlements without considering expenses.
• Forgetting that self-employment tax and income tax are two separate amounts.
• Spending the tax account on repairs or fuel.
• Assuming the due dates are the same every year without checking.
• Skipping a payment because income was low one quarter, without checking the rules.
• Forgetting state estimated taxes.
• Keeping poor records, so net earnings are only a guess.

This guide explains concepts and is not tax, legal or financial advice. Confirm your numbers and deadlines with the IRS and a qualified tax professional.