The IRS charges penalties to business owners who do not pay their self-employment taxes on time. Self-employment taxes are payments to Social Security and Medicare funds that are due on income earned by self-employed individuals. In a conventional work arrangement, the employee pays half of the tax due and the employer the other half. Self-employed individuals are both employers and employees, so they are responsible for paying the entire amount.

Underpayment Penalty

If you do not pay your self-employment tax by April 15 of the year following the tax year, you are liable for a penalty of 2.66 percent of the total amount you owe. Calculate this penalty first by figuring your self-employment tax, which is equal to 15.3 percent of your net business income up to $106,800, and then multiplying the amount of tax you owe by .0266.

Payments Made Before April 15

If you pay your self-employment tax late, but earlier than April 15 of the year following the tax year, you will owe a smaller self-employment tax penalty than if you paid on or after April 15. Count the number of days before April 15 that you made your payment. Multiply the number of days by .00011. Subtract this amount from the original amount of your penalty.

Prorated Penalties

The amount of your self-employment tax penalty is subject to the consideration that you have accrued the penalty over the course of the year. In addition, seasonal businesses earn a disproportionate amount of their incomes during selected months, so they owe more for their busy quarters than for their slower periods. You may adjust your self-employment tax penalty to reflect these factors by completing the worksheet on IRS Form 2210, which allows you to divide your income by quarters, and calculate the percentage of the total penalty that you owe for that period.

Other Considerations

If you are married and filing jointly, and your spouse arranges his deductions to cover your self-employment tax, you may not owe penalties even if you do not send in your own estimated tax payments.