The business structure you choose determines how much tax you pay, how much liability protection you have, and how much paperwork you deal with. For many small business owners, the wrong structure costs thousands of dollars every year in unnecessary taxes.
This isn't a theoretical exercise. A freelancer earning $120,000 as a sole proprietor pays roughly $17,000 in self-employment tax alone. That same person, structured as an S-Corp with a $70,000 salary, pays approximately $10,700 in payroll tax — saving over $6,000 annually. Same income. Same work. Different structure. Different tax bill.
This guide breaks down the three most common business structures — sole proprietorship, LLC, and S-Corp — explains exactly how each one is taxed, and helps you determine which structure saves you the most money at your income level.
Sole Proprietorship: The Default Starting Point
If you earn self-employment income and haven't filed any paperwork to create a business entity, you're a sole proprietor. This is the default structure — it exists automatically.
How it works:
You and your business are the same legal entity. You report business income and expenses on Schedule C of your personal tax return (Form 1040). There's no separate business tax return.
How it's taxed:
All net business income (revenue minus deductible expenses) is subject to two taxes:
Federal income tax. Your business profit flows directly onto your personal return and is taxed at your marginal rate (10% to 37% depending on your total taxable income).
Self-employment tax. 15.3% on 92.35% of your net self-employment income. This breaks down to 12.4% for Social Security (on income up to approximately $168,600) and 2.9% for Medicare (on all income, no cap). If your self-employment income exceeds $200,000 (single) or $250,000 (married), you also owe an additional 0.9% Medicare tax.
You can deduct 50% of the self-employment tax as an above-the-line adjustment on your personal return, which reduces your income tax slightly. But you still pay the full self-employment tax.
Example: You earn $100,000 in net business income as a sole proprietor.
Self-employment tax: $100,000 x 92.35% x 15.3% = $14,130 Federal income tax: Varies by total income and filing status, but let's estimate $15,000 Total: approximately $29,130
Advantages:
- Zero setup cost or paperwork
- No separate business tax return
- Simple bookkeeping
- Full control, no formalities
- All business losses deduct directly against other personal income
Disadvantages:
- No liability protection — your personal assets are exposed to business debts and lawsuits
- All profit is subject to self-employment tax
- Harder to raise capital or bring on partners
- Perceived as less professional by some clients and vendors
Best for: New businesses, side hustles, very small operations, businesses with low profit (under $40,000-$50,000), and anyone testing a business idea before committing to a formal structure.
LLC: Liability Protection Without Changing Taxes
An LLC (Limited Liability Company) is a legal entity created by filing articles of organization with your state. It provides liability protection — separating your personal assets from business debts and obligations.
The critical thing most people misunderstand about LLCs:
An LLC is a legal structure, not a tax structure. By default, a single-member LLC is taxed exactly like a sole proprietorship. The IRS ignores it for tax purposes — it's what they call a "disregarded entity." A multi-member LLC is taxed as a partnership by default.
Forming an LLC does not change your taxes. It changes your liability protection.
How a single-member LLC is taxed (default):
Exactly like a sole proprietorship. All net income goes on Schedule C. You pay income tax and self-employment tax on the full amount. The only difference is legal liability protection.
How a multi-member LLC is taxed (default):
As a partnership. The LLC files Form 1065 (informational return) and issues each member a K-1 showing their share of income. Each member reports their share on their personal return and pays income tax and self-employment tax on their distributive share (assuming they're active members).
The LLC's tax flexibility:
Here's where LLCs become powerful — they can elect to be taxed as different entities:
- Default: Disregarded entity (single-member) or partnership (multi-member)
- Election: S-Corporation (by filing Form 2553)
- Election: C-Corporation (by filing Form 8832)
This flexibility means you can form an LLC for liability protection and then choose the tax treatment that saves you the most money. Most small business owners who want S-Corp tax treatment form an LLC and elect S-Corp status rather than forming a separate corporation.
Costs:
State filing fees range from $50 to $500 depending on your state. Some states charge an annual LLC fee or franchise tax (California charges $800 per year regardless of income, which is significant for low-revenue businesses).
Advantages:
- Liability protection — personal assets are shielded from business debts
- Tax flexibility — can elect S-Corp or C-Corp treatment
- Relatively simple to form and maintain
- Fewer formalities than a corporation (no board of directors, no annual meetings required in most states)
- Members can set flexible ownership and profit-sharing arrangements
Disadvantages:
- State filing fees and potential annual fees
- Some states impose additional LLC taxes (California, Texas, others)
- By itself (without S-Corp election), provides no tax advantage over sole proprietorship
- Requires maintaining separation between personal and business finances
- Some states require an operating agreement
Best for: Any business owner who wants liability protection. Essentially everyone who's moved past the hobby or testing phase should have at least an LLC. The liability protection alone justifies the cost.
S-Corporation: The Tax Optimization Structure
An S-Corporation is a tax election, not a type of entity. You can become an S-Corp in two ways:
- Form a corporation and elect S-Corp status (file Form 2553 with the IRS)
- Form an LLC and elect S-Corp status (also file Form 2553)
Most small business owners choose option 2 — forming an LLC taxed as an S-Corp. This gives you the legal simplicity of an LLC with the tax benefits of an S-Corp.
How S-Corp taxation works:
This is the key difference. As a sole proprietor or default LLC, all your business profit is subject to self-employment tax (15.3%). As an S-Corp, you split your income into two categories:
Salary (reasonable compensation). You pay yourself a W-2 salary for the work you do. This salary is subject to payroll taxes — the same 15.3% (split between employer and employee portions). The S-Corp pays the employer half (7.65%), and you pay the employee half (7.65%).
Distributions. After paying yourself a salary, remaining profits can be taken as shareholder distributions. These distributions are subject to income tax but NOT subject to self-employment or payroll tax.
This is where the savings happen. You only pay payroll tax on your salary, not on the full profit.
Example: Your business earns $150,000 in net profit.
As a sole proprietor: Self-employment tax: $150,000 x 92.35% x 15.3% = $21,189 Income tax: approximately $22,000 (varies by situation) Total: approximately $43,189
As an S-Corp with $70,000 salary: Payroll tax on salary: $70,000 x 15.3% = $10,710 Income tax on full $150,000: approximately $22,000 (same — the total income is identical) Total: approximately $32,710
Savings: approximately $10,479 per year
The $80,000 in distributions ($150,000 profit minus $70,000 salary) is subject to income tax but avoids the 15.3% self-employment/payroll tax. That's $80,000 x 15.3% x 92.35% = $11,300 that would have been self-employment tax — now it's zero.
The "Reasonable Compensation" Requirement
The IRS requires S-Corp owners to pay themselves a "reasonable salary" — what you'd pay someone to do your job. You can't pay yourself a $20,000 salary on $200,000 in profits and take $180,000 as distributions. The IRS will reclassify the excess distributions as wages and charge back payroll taxes, plus penalties.
What's "reasonable" depends on:
- Your industry
- Your experience and qualifications
- Time spent working in the business
- Comparable salaries for similar roles
- Revenue and profitability of the business
- Geographic location
A CPA helps you determine the right salary — high enough to satisfy the IRS, low enough to maximize tax savings. Common benchmarks suggest salary should be roughly 40-60% of net business profit, but this varies significantly by industry and situation.
S-Corp requirements and costs:
Separate tax return. S-Corps file Form 1120-S annually, even if you're the only owner. This is more complex than Schedule C.
Payroll. You must run payroll for your salary — withholding income tax, Social Security, and Medicare. This means payroll processing (software or service), quarterly payroll tax filings (Form 941), and annual forms (W-2, W-3).
State requirements. Some states impose additional taxes or fees on S-Corps. Some states don't recognize S-Corp status at all (requiring a separate state return as a C-Corp).
Reasonable compensation analysis. You should document how you determined your salary is reasonable, in case of an IRS inquiry.
Typical additional costs:
- Payroll service: $30-$100/month
- S-Corp tax return preparation: $500-$2,000 (compared to $200-$500 for Schedule C)
- State filing fees: varies
The total additional cost of operating as an S-Corp is typically $1,500-$4,000 per year compared to a sole proprietorship or default LLC. This means the S-Corp election only makes sense if your tax savings exceed this additional cost.
The break-even point:
Most CPAs recommend considering the S-Corp election when net business profit consistently exceeds $50,000-$60,000 per year. Below that level, the tax savings may not justify the additional complexity and cost. Above that level, the savings grow quickly.
At $80,000 profit, savings might be $3,000-$5,000 (minus $2,000-$3,000 in added costs = net savings of $1,000-$2,000). At $120,000 profit, savings might be $6,000-$8,000 (minus costs = net savings of $4,000-$5,000). At $200,000 profit, savings might be $12,000-$18,000 (minus costs = net savings of $10,000-$15,000).
The higher your profit, the more the S-Corp saves.
Advantages:
- Significant self-employment tax savings at higher income levels
- Salary creates W-2 income (helpful for mortgage applications, loan qualifications)
- More credibility with some clients and lenders
- Same liability protection as an LLC (if using LLC taxed as S-Corp)
- Can still take the Qualified Business Income (QBI) deduction on distributions
Disadvantages:
- More expensive to operate (payroll, tax prep, state fees)
- More complex compliance (separate tax return, payroll filings)
- Reasonable compensation scrutiny from IRS
- Limited to 100 shareholders, one class of stock, US resident shareholders only
- Losses are limited by basis, at-risk, and passive activity rules
- Some states impose additional S-Corp taxes
Best for: Self-employed individuals and business owners with consistent net profit above $50,000-$60,000 who want to minimize self-employment tax while maintaining pass-through taxation.
C-Corporation: The Corporate Structure
A C-Corporation is a fully separate legal and tax entity. It files its own tax return (Form 1120) and pays tax at a flat 21% corporate rate.
How it's taxed:
The corporation pays tax on its profits at 21%. When those profits are distributed to shareholders as dividends, the shareholders pay tax again — at the qualified dividend rate (0%, 15%, or 20% depending on income). This is called double taxation.
Example: Your C-Corp earns $200,000 in profit. Corporate tax: $200,000 x 21% = $42,000 After-tax profit: $158,000 If distributed as qualified dividends at 15% rate: $158,000 x 15% = $23,700 Total tax: $42,000 + $23,700 = $65,700 (32.85% effective rate)
Compare that to an S-Corp where the same $200,000 passes through and is taxed at your personal rate (say 24%) plus payroll tax on salary. The S-Corp typically wins for small businesses that distribute their profits.
When does a C-Corp make sense?
Retained earnings. If you reinvest most profits back into the business rather than distributing them, the 21% corporate rate may be lower than your personal marginal rate (22%, 24%, 32%, etc.). You're only taxed at the corporate level until you distribute.
Equity compensation. C-Corps can issue stock options, restricted stock, and other equity compensation more flexibly. If you plan to raise venture capital or bring on equity partners, a C-Corp (specifically a Delaware C-Corp) is the standard structure.
Going public or seeking acquisition. Buyers and public markets expect C-Corp structure.
Qualified Small Business Stock (QSBS). C-Corp stock that meets certain requirements qualifies for Section 1202 exclusion — potentially excluding up to $10 million (or 10x your basis) in capital gains from tax when you sell the stock. This is enormously valuable for startup founders.
Fringe benefits. C-Corp owner-employees can receive certain tax-free fringe benefits (health insurance, life insurance, disability insurance) that aren't available to S-Corp shareholders owning more than 2%.
Best for: Businesses planning to raise outside investment, companies retaining significant earnings for growth, startups pursuing the QSBS exclusion, and businesses planning an eventual sale or IPO.
Side-by-Side Comparison
Here's how the three main structures compare across key factors:
Liability Protection
- Sole Proprietorship: None
- LLC: Yes
- S-Corp (LLC election): Yes
- C-Corp: Yes
Self-Employment Tax on All Profit
- Sole Proprietorship: Yes (15.3%)
- LLC (default): Yes (15.3%)
- S-Corp: Only on salary
- C-Corp: No (but double taxation on distributions)
Separate Tax Return Required
- Sole Proprietorship: No (Schedule C)
- LLC (default): No (Schedule C for single-member)
- S-Corp: Yes (Form 1120-S)
- C-Corp: Yes (Form 1120)
Payroll Required
- Sole Proprietorship: No
- LLC (default): No
- S-Corp: Yes
- C-Corp: Yes
QBI Deduction Available
- Sole Proprietorship: Yes
- LLC (default): Yes
- S-Corp: Yes
- C-Corp: No
Annual Cost to Maintain
- Sole Proprietorship: Minimal
- LLC (default): $100-$800/year
- S-Corp: $2,000-$5,000/year
- C-Corp: $2,000-$5,000/year
Tax Return Preparation Cost
- Sole Proprietorship: $200-$500
- LLC (default): $200-$500
- S-Corp: $500-$2,000
- C-Corp: $500-$2,000
When to Switch Structures
The right structure changes as your business grows. Here's the typical progression:
Starting out ($0-$40,000 profit): Sole proprietorship or single-member LLC. Keep it simple. Focus on building the business. The tax savings from an S-Corp at this income level don't justify the complexity.
Growing ($40,000-$60,000 profit): Form an LLC if you haven't already (for liability protection). Start having conversations with a CPA about whether S-Corp election makes sense. Run the numbers.
Established ($60,000+ profit): Strongly consider S-Corp election. At this level, the annual tax savings typically exceed the added costs by a meaningful margin, and the gap widens with every dollar of additional profit.
High growth (raising capital, planning exit): Consider C-Corp status, particularly for QSBS benefits, equity compensation, and investor expectations.
Timing matters. The S-Corp election must be filed by March 15 of the year you want it to take effect (for calendar-year taxpayers) using Form 2553. If you miss the deadline, the IRS allows late election relief in many cases, but don't count on it. Plan ahead.
If you're already operating as a sole proprietor or LLC, switching to S-Corp is straightforward — file Form 2553 with the IRS. You don't need to dissolve your LLC. You're simply changing how the IRS taxes it. However, there are transition considerations (opening balance sheet, asset basis, accounting method) that a CPA should handle.
Common Mistakes in Choosing a Structure
Forming an LLC and assuming it saves taxes. It doesn't — not by itself. An LLC taxed as a disregarded entity pays identical taxes to a sole proprietor. The LLC provides liability protection, not tax savings. Tax savings come from the S-Corp election.
Electing S-Corp too early. If your business earns $30,000 in profit, the S-Corp's additional costs ($2,000-$4,000 in payroll processing and tax prep) may eat up most or all of the tax savings. Wait until the math clearly favors S-Corp.
Setting salary too low. Paying yourself a $30,000 salary when you do the same work that would pay $80,000 in the market is a red flag. The IRS can reclassify distributions as wages, and you'll owe back payroll taxes plus penalties and interest.
Setting salary too high. Paying yourself 100% of profits as salary eliminates the S-Corp tax benefit. The whole point is having distributions that avoid payroll tax.
Ignoring state-level impacts. Some states charge additional taxes on S-Corps, don't recognize S-Corp status, or impose minimum franchise taxes. California charges a 1.5% S-Corp tax on net income (minimum $800). Factor state rules into your decision.
Not considering the QBI deduction interaction. The Qualified Business Income deduction (Section 199A) lets pass-through business owners deduct up to 20% of qualified business income. For S-Corps, only the distribution portion qualifies for QBI — not salary. Your salary level affects your QBI deduction, which adds another variable to the optimization.
Going it alone. Entity selection involves the interaction of income tax brackets, self-employment tax, payroll tax, QBI deduction, state taxes, compliance costs, and your personal financial situation. This is not a DIY decision. The cost of a CPA consultation ($200-$500) is trivial compared to the potential annual tax savings.
How a CPA Determines Your Optimal Structure
A CPA evaluating your entity structure will:
- Analyze your current and projected net business income
- Calculate your tax liability under each structure (sole prop, LLC, S-Corp, C-Corp)
- Determine the optimal salary for S-Corp purposes
- Factor in state-specific taxes and fees
- Calculate the QBI deduction under each scenario
- Account for compliance costs (payroll, tax prep, state fees)
- Consider your personal tax situation (other income, filing status, deductions)
- Model multi-year projections (not just this year)
- Recommend the structure that produces the lowest total tax after accounting for all costs
The right structure isn't the same for every business. It depends on your specific numbers. What saves your neighbor $10,000 might cost you money if your income, state, or situation is different.
Find a CPA who specializes in small business entity selection and tax planning at ListMyCpa.com. Search by state, city, and specialization to connect with someone who can run the numbers for your specific situation.