Self-Employment Tax, Explained

If you work for yourself, you owe self-employment tax on top of regular income tax - and it usually comes as a shock the first year, because no employer was quietly taking it out of a paycheck along the way. Self-employment tax is your share and the employer's share of Social Security and Medicare, combined into one tax: 15.3%, made up of 12.4% for Social Security (which applies only up to an annually-adjusting wage base cap) and 2.9% for Medicare (which has no cap). It's calculated on Schedule SE and filed with your federal Form 1040. This is separate from, and in addition to, whatever federal and state income tax you owe on your profit.

Why you pay "both halves"

When you work as someone's employee, Social Security and Medicare tax is split: your employer pays half and withholds the other half from your wages. When you work for yourself, there is no employer to split it with - the law (the Self-Employment Contributions Act, or SECA) makes you responsible for the full 15.3%. That's the whole story behind the number that surprises so many new freelancers and small business owners: it isn't a penalty for being self-employed, it's simply both halves of the same Social Security and Medicare tax an employee and their employer would otherwise split.

The 12.4% Social Security portion only applies up to a wage base that the Social Security Administration adjusts every year, so income above that cap for the year isn't hit with the Social Security piece (though it still owes the 2.9% Medicare piece, which has no ceiling). Because that dollar cap changes annually, don't rely on a number you saw last year or in an old article - confirm the current wage base directly on irs.gov before you estimate what you owe. High earners should also know there's an additional Medicare tax that can kick in above certain income thresholds; again, confirm the current thresholds on irs.gov rather than assuming.

Who actually owes it

• Sole proprietors and independent contractors - if you file a Schedule C for your business profit, that net profit is generally subject to self-employment tax.
• General partners in a partnership, on their share of partnership income from the business's trade or activity.
• Most LLC members - a single-member LLC is, by default, a "disregarded entity" taxed just like a sole proprietorship (Schedule C), and a multi-member LLC is, by default, taxed as a partnership. Forming an LLC changes your personal liability exposure; it does not, by itself, change how you're taxed or make self-employment tax go away.
• Not typically owed on money you take as a wage-earning employee (that's regular FICA withholding instead), and there are some narrower exceptions - for example, certain limited partners and some rental or investment income are treated differently. If your situation doesn't fit neatly into "I run a business and get paid for my own work," it's worth a few minutes with a CPA or the IRS's own guidance rather than guessing.

The one built-in break: you deduct the "employer half"

The tax code does soften this somewhat. Because an employee's employer would normally get to deduct its half of FICA as a business expense, the law lets a self-employed person deduct the equivalent "employer half" of their self-employment tax - generally half of what you calculate on Schedule SE - as an adjustment to income (an "above-the-line" deduction) on Schedule 1 of Form 1040. You get this whether or not you itemize. It doesn't erase the self-employment tax itself, but it does lower the income tax you owe on top of it.

Separately, many self-employed people and small business owners with qualifying pass-through income can also deduct up to 20% of their qualified business income under the Section 199A / QBI deduction - a different break aimed at income tax, not self-employment tax, and one with its own eligibility rules, business-type limits, and income phase-outs that can change. Whether you qualify, and for how much, depends on your specific business and income - a CPA or the Form 8995 instructions on irs.gov can walk you through it.

Quarterly estimated taxes: the deadline nobody warns you about

Because no one withholds tax from self-employment income as you earn it, the IRS generally expects you to pay both your income tax and your self-employment tax yourself, in advance, in quarterly installments using Form 1040-ES - rather than waiting to settle up in one lump sum the following spring. Miss this and you can owe an underpayment penalty even if you pay everything in full by the filing deadline. The exact due dates and safe-harbor rules (how much you need to have paid in, and by when, to avoid a penalty) are set by the IRS and can shift slightly year to year, so confirm the current-year quarterly due dates and safe-harbor thresholds on irs.gov rather than assuming they match last year.

How an S-corp election can reduce self-employment tax

This is the main reason profitable small business owners look at electing S-corporation tax treatment. Here's the framework, kept honest:

• An LLC or a corporation can elect to be taxed as an S-corp for federal purposes. That's a tax classification (an IRS election, typically via Form 2553); the entity itself is still formed and governed under your state's law.
• If you're taxed as an S-corp and you work in the business, you're generally required to pay yourself a reasonable salary as a W-2 employee. That salary is subject to regular FICA payroll tax (split between "you" as owner and "you" as employer, but functionally the same 15.3% on that piece).
• Profit distributed to you beyond that reasonable salary is generally not subject to self-employment tax or FICA - only income tax. That's the potential savings.
• The catch: the IRS requires the salary to be genuinely "reasonable" for the work performed, and it actively scrutinizes S-corps that pay an unrealistically low salary and call the rest a distribution just to dodge payroll tax. Get this wrong and you risk back taxes, penalties, and interest. There are also real costs and complexity to running payroll and a separate corporate return that can outweigh the savings for a smaller or less profitable business.

Whether an S-corp election makes sense for you depends on your profit level, your state's rules, and payroll costs - this is a "run the numbers with a CPA" decision, not a do-it-yourself one.

What to do

1. Track your net profit throughout the year - self-employment tax is calculated on net earnings (income minus business expenses), not gross revenue.
2. Set aside money as you earn it. Many self-employed people set aside a meaningful chunk of every payment they receive specifically for taxes, since none of it is being withheld for you.
3. File Schedule SE along with your Schedule C (or partnership/S-corp return, as applicable) each year to calculate what you owe.
4. Pay quarterly estimated taxes using Form 1040-ES if you expect to owe a meaningful amount for the year - check irs.gov for the current due dates and safe-harbor rules.
5. Claim the above-the-line deduction for the employer-equivalent half of your self-employment tax on Schedule 1, and ask a CPA whether you qualify for the QBI deduction.
6. Ask a CPA about an S-corp election once your business is consistently profitable enough that the payroll and compliance costs would be worth it - don't file the election on your own without understanding the reasonable-salary requirement.

State income tax is a separate matter and varies by state - some states have no income tax at all, and none of them change your federal self-employment tax obligation. Check your state's tax agency for what you owe there.

A quick word on what this article isn't about: this covers your own self-employment tax as a business owner. If you also hire workers, the taxes you withhold from their paychecks are trust-fund money that belongs to the government the moment it's withheld - mishandling that is a much more serious problem than an S-corp salary question, and it's covered separately. And whether someone who works for you is legally an employee or an independent contractor is a factual, legal question - not something you get to choose by job title or contract - because misclassifying a worker to avoid payroll tax can create significant back-tax and wage liability.

Frequently asked questions

Do I owe self-employment tax if my business lost money?

No. Self-employment tax is calculated on net profit. If your business had a net loss for the year, you generally don't owe self-employment tax (though you still file the return, and losses can affect other parts of your taxes).

Is self-employment tax the same as income tax?

No. They're two separate calculations that both apply to your business profit. Self-employment tax funds Social Security and Medicare; income tax is calculated separately on your total taxable income (business profit plus any other income, minus deductions) at ordinary income tax rates.

Does forming an LLC lower my self-employment tax?

Not by itself. An LLC's default federal tax treatment mirrors a sole proprietorship (single-member) or a partnership (multi-member) - both of which are generally subject to self-employment tax the same as before. Any self-employment tax savings comes from electing S-corp taxation, which an LLC can also choose to do, not from forming the LLC alone.

What happens if I don't pay quarterly estimated taxes?

You can owe an underpayment penalty in addition to the tax itself, even if you pay everything by the filing deadline. The specific penalty calculation and safe-harbor rules for avoiding it are set by the IRS and can change, so check the current rules on irs.gov before deciding to skip quarterly payments.

Do I owe self-employment tax on income from an LLC taxed as a partnership if I'm not actively involved?

It depends on your role and how the partnership income is characterized - general partners are typically subject to self-employment tax on their distributive share, while some limited partners and passive investors may not be, under specific and fairly technical rules. This is a good question to bring to a CPA rather than assume either way.

This article is general business and tax information, not legal, tax, or financial advice, and does not create an attorney-client or accountant-client relationship. For guidance specific to your situation, consult a qualified CPA or tax attorney, or use free resources from the IRS, the U.S. Small Business Administration, SCORE, or your state's Small Business Development Center.