The self-employment tax is one of the biggest and least-understood numbers on a business owner's tax return. It's not federal income tax. It's not state income tax. It's the Social Security and Medicare (FICA) tax that W-2 employees split with their employer — except that when you're self-employed, you pay both halves yourself.
For an owner pulling $200,000 in business profit, the self-employment tax bill can exceed $25,000 annually. That's often more than the federal income tax bill on the same income, because self-employment tax kicks in at the first dollar and has no standard deduction blunting its impact. Understanding how entity choice affects this single line item is worth more to most owners than nearly any other tax planning decision they'll make.
What the Self-Employment Tax Actually Is
Self-employment tax (SE tax) has two components:
- Social Security portion: 12.4% of net self-employment earnings, up to the annual Social Security wage base (adjusted yearly; approximately $168,600 in 2024).
- Medicare portion: 2.9% of net self-employment earnings, with no cap.
- Additional Medicare tax: An extra 0.9% on earnings above $200,000 (single) or $250,000 (married filing jointly), added in 2013.
The combined rate is 15.3% on the first tranche of income, dropping to 2.9% (or 3.8% at high incomes) after the Social Security wage base is hit. Employees and employers each pay half of these amounts on W-2 wages. Self-employed people pay both halves on their Schedule SE.
SE tax is calculated on 92.35% of net self-employment earnings (a small technical adjustment that serves as an approximation of the employer's deductible share). You also get to deduct one-half of SE tax as an adjustment to income on your 1040 — meaningful at higher incomes, but still leaves you paying more total FICA than a W-2 employee earning the same.
How Each Entity Classification Handles FICA Taxes
Sole proprietorship / single-member LLC: All net profit from Schedule C is subject to SE tax. There's no way to split profits into wage and non-wage components. If the business made $150,000 after expenses, you pay SE tax on all $150,000 (adjusted by the 92.35% factor).
Partnership / multi-member LLC: Active partners pay SE tax on their share of partnership income. Limited partners generally don't, and LLC members who are more passive investors have more nuanced treatment (the regulations are old and contested). If you're actively running the business, assume SE tax applies to your share.
C corporation: The corporation pays salaries to employees (including owner-employees) and those salaries are subject to FICA — but the split of cost is between employer (corporation) and employee. The corporation pays 7.65% (employer half) and withholds 7.65% from the employee's paycheck. That's the same cost structure as an S corp salary, and in aggregate it's the same 15.3% total FICA on W-2 wages. Corporate dividend distributions to shareholders are not subject to FICA. So the FICA story for a C corp owner is: only your W-2 salary is exposed to payroll taxes; dividends are exempt (though subject to their own income tax treatment).
S corporation: The big win. Shareholder-employees are required to pay themselves reasonable compensation as W-2 wages. Those wages are subject to FICA. Remaining profits flow through to the shareholder as distributions and are not subject to SE tax or FICA. If your reasonable compensation is $90,000 and the business earns another $110,000 in distributable profit, you pay FICA on the $90,000 and save the 15.3% (approximately) on the $110,000 — worth roughly $16,800 per year.
The Reasonable Compensation Problem
The S corp strategy works only to the extent your W-2 compensation is defensible as "reasonable." The IRS has litigated this issue repeatedly and has won in case after case where shareholder-employees paid themselves artificially low salaries.
Reasonable compensation is what you would have to pay an unrelated third party to do the work you do for the business. The factors courts and the IRS consider include:
- Your training and experience
- Your duties and responsibilities
- Time and effort devoted to the business
- Compensation paid to non-shareholder employees in similar positions
- Compensation paid by comparable businesses
- The business's economic condition
You can justify lower salaries in a lower-profit year. You can't justify paying yourself $30,000 when the business is generating $500,000 in profit. The common heuristic is that reasonable compensation should roughly track what you'd pay a general manager to run the business without an ownership stake — which scales with revenue and complexity.
Documentation matters. If you're aggressive on the spread between salary and distributions, keep a file with your compensation study, comparable salary data, and board minutes approving the compensation.
The Benefits You Give Up
Paying less into Social Security isn't free money. Social Security benefits are calculated based on your 35 highest-earning years of FICA-covered earnings. If you consistently pay yourself a $40,000 S corp salary instead of drawing $150,000 as a sole proprietor, you'll have lower Social Security retirement benefits decades from now.
The math is complicated because Social Security is progressive — the benefit formula replaces a higher percentage of low earnings than high earnings. For most owners, the present-value savings from the SE tax reduction exceed the present-value loss in future benefits, especially at higher income levels where you're already over the wage base cap and paying only the Medicare portion on the excess. But for lower-income owners who would otherwise pay into Social Security near or below the wage base, the calculation is closer.
Disability and survivor benefits are also tied to covered earnings. An owner who minimizes W-2 wages may find their disability benefit lower if they ever need to claim it.
The Additional Medicare Tax and Net Investment Income Tax
Two surtaxes catch higher-income owners in ways that depend on entity structure:
Additional Medicare Tax (0.9%): Applies to earned income over $200,000 (single) / $250,000 (MFJ). S corp distributions are not earned income. Partnership income from active participation is.
Net Investment Income Tax (3.8%): Applies to investment income (dividends, interest, capital gains, passive rental) for high earners. S corp distributions from an active business generally are not investment income. Passive investment income and passive rental are. This is a big reason the active/passive characterization of rental property matters — see 8.4.
The interaction is that an S corp shareholder-employee who is materially involved in the business can often get net profits past a certain level to flow through as distributions that are neither FICA-subject nor NIIT-subject. A passive investor in the same business doesn't get that advantage.
When the S Corp Strategy Doesn't Work
Several situations make the S corp election less attractive even when the math looks favorable:
Low profitability. If reasonable compensation is close to total income, there's little room for tax-favored distributions.
Multiple state operations. Some states don't recognize the S corp election for state tax purposes (notably New Hampshire, Tennessee, and previously others). California imposes a 1.5% franchise tax on S corp income on top of individual tax.
Health insurance. 2%+ S corp shareholders can't take certain pre-tax fringe benefits that are available to C corp owner-employees. Health insurance premiums paid for shareholders are added to W-2 wages (though deductible on the personal return).
Retirement plan contributions. Some retirement plan calculations are based on W-2 compensation. An artificially low S corp salary can reduce retirement plan contribution capacity. See Category 3 for the mechanics — this is a real and often-overlooked trade-off.
Desire for tax-favored sale of goodwill. In an asset sale, personal goodwill (tied to the owner) can receive capital gain treatment separate from the corporate assets. The C corp vs. S corp treatment of this differs in ways that matter on exit.
The FICA Cost of Paying Your Spouse and Kids
Entity choice also shapes how family members can be paid. A sole proprietor can hire their child under 18 and pay them without owing FICA on those wages (children under 18 working for a parent's sole proprietorship or parent-owned partnership are FICA-exempt). That same exemption doesn't apply to children working for a corporation, even if the corporation is entirely owned by the parent. Sole proprietors and partnerships have a unique edge here.
Paying a spouse raises similar structural questions. A spouse paid as a W-2 employee of your business owes FICA on those wages and so does the business. A spouse who's a partner in an LLC partnership pays SE tax on partnership distributions. If the spouse is on your health plan, the interaction with S corp 2%+ shareholder rules gets complicated.
Running the Actual Numbers
The one practical action for most owners is to run their own numbers once a year, not relying on a general rule. Here's the calculation:
- Estimate your net business income for the year.
- Subtract reasonable W-2 compensation you would pay yourself as an S corp owner.
- The remainder is your potential S corp distribution.
- Multiply the distribution amount by 15.3% (or 2.9% if you're already over the Social Security wage base).
- Subtract estimated S corp administrative costs (payroll, tax prep, state franchise tax).
- The net is the actual annual benefit of the S corp election.
If that number is materially positive and you're comfortable defending your reasonable compensation figure, the S corp election generally makes sense. If it's small or negative, stay where you are.
Review this calculation any year your income changes materially. The answer changes as the business grows.