As a sole proprietor or single-member LLC, your business is what the IRS calls a pass-through entity. That means the business itself does not file a separate tax return or pay its own taxes. Instead, the profit passes through to your personal tax return and gets taxed there.

The profit from your business goes on Schedule C, which is part of your Form 1040. You report your gross income, subtract your business expenses, and the result is your net profit. That net profit number is what gets taxed.

Here is where it gets important to understand. That net profit faces two separate taxes. First is regular federal income tax at whatever bracket you fall into based on your total income. Second is self-employment tax, which is 15.3 percent of your net profit. That 15.3 percent covers Social Security and Medicare, the same taxes that get withheld from a W-2 paycheck. When you work for yourself, you pay both the employee and employer portions.

The self-employment tax is calculated on Schedule SE and added to your 1040. You do get a small break because you can deduct half of the self-employment tax when calculating your adjusted gross income. But 15.3 percent of your profit still adds up quickly, especially as your business grows.

Because nothing is withheld throughout the year like it would be from a paycheck, the IRS expects you to pay quarterly estimated taxes. These are due in April, June, September, and January. If you do not pay enough during the year, you will owe a penalty on top of the tax itself. Getting the estimates right requires knowing what your profit will look like, which means keeping your books current so you are not guessing.

This is exactly the kind of work we handle for owner-operated service businesses. Simona Leppala is a CPA and Enrolled Agent who manages the small business bookkeeping services that feed accurate numbers into your Schedule C, prepares your personal tax return including that Schedule C, and helps you plan throughout the year so the quarterly estimates are set correctly. Everything stays in-house with someone who understands how these pieces connect.

If your business is growing and the self-employment tax is starting to feel heavy, that is worth a conversation about tax strategy. There are timing decisions, deduction opportunities, and retirement account options that can lower what you owe. The key is planning ahead rather than discovering the bill at filing time.

If you have questions about how this applies to your specific situation, reach out for a consultation. Every business is different, and getting the details right from the start saves money and headaches later.