Small Business Tax Guide: LLC, S-Corp, Sole Prop & More
Data Notice: Figures, rates, and statistics cited in this article are based on the most recent available data at time of writing and may reflect projections or prior-year figures. Always verify current numbers with official sources before making financial, medical, or educational decisions.
Small Business Tax Guide: LLC, S-Corp, Sole Prop & More
This article is for informational purposes only and does not constitute tax advice. Consult a qualified tax professional for your specific situation.
There are approximately ~33.2 million small businesses in the United States, and the vast majority are pass-through entities — sole proprietorships, partnerships, LLCs, and S-Corporations — where business income flows through to the owner’s personal tax return. The entity structure you choose determines how much you pay in self-employment tax, how you take money out of the business, what deductions you qualify for, and how the IRS audits you. Choosing the wrong structure can cost small business owners thousands of dollars per year in unnecessary taxes.
This guide covers the tax implications of every major business entity type, walks through self-employment tax calculations, explains quarterly estimated payments, catalogs the most valuable business deductions, and provides decision frameworks for entity selection. Whether you are a freelancer earning ~$40,000 on the side, a consultant billing ~$200,000 annually, or a growing business with employees, this guide will help you understand your tax obligations and minimize your burden.
Business Entity Types: Tax Comparison
Sole Proprietorship
A sole proprietorship is the default structure for any individual operating a business without forming a separate legal entity. There is no formal registration required (beyond local business licenses). All income and expenses are reported on Schedule C of your personal Form 1040.
Tax Treatment:
- All net business income is subject to federal income tax at your marginal rate (~10%–~37%).
- All net business income is subject to self-employment tax (~15.3% on the first ~$176,100 of net earnings, ~2.9% on earnings above that, plus ~0.9% Additional Medicare Tax above ~$200,000 single / ~$250,000 MFJ).
- You can deduct ~50% of self-employment tax as an above-the-line deduction.
- Eligible for the ~20% Qualified Business Income (QBI) deduction, subject to income limitations.
Example: A sole proprietor with ~$100,000 in net business income (after all Schedule C deductions):
| Tax Component | Amount |
|---|---|
| Self-employment tax (~15.3% on | ~$14,130 |
| Deductible half of SE tax | (~$7,065) |
| AGI for income tax purposes | ~$92,935 |
| QBI deduction (~20% × ~$100,000) | (~$20,000) |
| Taxable income (after ~$15,700 standard deduction) | ~$57,235 |
| Federal income tax (approximate, single) | ~$7,816 |
| Total federal tax | ~$21,946 |
Pros: Simplest structure, lowest compliance costs, no separate tax return. Cons: Highest self-employment tax exposure, no liability protection.
Single-Member LLC (Default Tax Treatment)
A single-member LLC is a “disregarded entity” for federal tax purposes. The IRS treats it exactly like a sole proprietorship — all income flows to Schedule C. The LLC provides legal liability protection but no tax benefit on its own.
Tax Treatment: Identical to sole proprietorship.
When It Matters: The LLC structure becomes tax-relevant when you elect to be taxed as an S-Corp (see below). Otherwise, the only benefit is legal liability protection, which is significant for business risk management but irrelevant for tax purposes.
S-Corporation
An S-Corporation is a tax election (not a business entity type) that changes how business income is taxed. You can form an S-Corp by incorporating a corporation and filing Form 2553, or by forming an LLC and electing S-Corp tax treatment. The key tax advantage is the ability to split income between salary and distributions.
Tax Treatment:
- The S-Corp itself files Form 1120-S (information return) but pays no entity-level tax.
- Owner-employees must pay themselves a “reasonable salary” for services performed. This salary is subject to FICA payroll taxes (~7.65% employee share + ~7.65% employer share = ~15.3%).
- Remaining profits are distributed to shareholders as distributions, which are not subject to self-employment or FICA tax.
- All income (salary + distributions) is subject to federal income tax.
- Eligible for the ~20% QBI deduction on qualified business income (distributions, not salary).
Example: Same ~$100,000 business income, structured as S-Corp with ~$60,000 salary and ~$40,000 distribution:
| Tax Component | Amount |
|---|---|
| FICA on ~$60,000 salary (~15.3% total, employer pays half) | ~$9,180 |
| Deductible employer share of FICA | (~$4,590) |
| QBI deduction (~20% × ~$40,000 distribution) | (~$8,000) |
| Taxable income (after ~$15,700 standard deduction) | ~$71,710 |
| Federal income tax (approximate, single) | ~$10,654 |
| Total federal tax | ~$19,834 |
| Savings vs. sole proprietorship | ~$2,112 |
The savings increase as income increases because a larger proportion of income can be classified as distributions rather than salary. At ~$200,000 in net business income (with ~$80,000 reasonable salary), the S-Corp advantage can exceed $8,000–$10,000 per year.
The “Reasonable Salary” Requirement: The IRS requires that S-Corp owner-employees pay themselves a salary that is reasonable for the services they perform. Setting the salary too low to maximize the distribution/SE-tax savings is a red flag for audit. The IRS considers factors like training, experience, duties, time committed, comparable salaries in similar businesses, and the company’s financial condition. A common guideline is to set salary at approximately ~50%–~60% of net income for service businesses, though this varies.
When S-Corp Makes Sense: Generally, when net business income consistently exceeds approximately $50,000–$60,000 per year and the SE tax savings outweigh the additional compliance costs (separate payroll, corporate tax return, potentially higher accounting fees of approximately $1,500–$3,000 per year).
For state-specific considerations, see our guides on business tax in Delaware and best states for small business taxes.
Partnership (Multi-Member LLC)
A multi-member LLC defaults to partnership taxation. The partnership files Form 1065 (information return) and issues Schedule K-1 to each partner. Each partner reports their share of income, deductions, and credits on their personal return.
Tax Treatment:
- No entity-level tax.
- General partners pay self-employment tax on their distributive share of partnership income.
- Limited partners generally do not pay self-employment tax on their distributive share (though guaranteed payments are subject to SE tax).
- Each partner’s share of income is subject to federal income tax.
- Eligible for QBI deduction on qualified business income.
Key Consideration: The partnership agreement determines how income, losses, and deductions are allocated among partners. Unlike S-Corps (which must allocate strictly based on ownership percentage), partnerships have flexibility to make “special allocations” — as long as they have “substantial economic effect” under IRS regulations.
C-Corporation
A C-Corporation is a separate taxpaying entity. It files Form 1120 and pays corporate income tax on its profits. When profits are distributed to shareholders as dividends, the shareholders pay tax on those dividends — creating “double taxation.”
Tax Treatment:
- Corporate income tax: flat ~21% on all taxable corporate income.
- Qualified dividends to shareholders are taxed at ~0%, ~15%, or ~20% (plus ~3.8% NIIT for high earners).
- Owner-employees receive W-2 wages, subject to FICA.
- Not eligible for QBI deduction (that is only for pass-through entities).
Example: ~$100,000 corporate profit, all distributed as dividends to a single shareholder in the ~22% bracket:
| Tax Component | Amount |
|---|---|
| Corporate income tax (~21%) | ~$21,000 |
| After-tax profit available for dividends | ~$79,000 |
| Shareholder tax on qualified dividends (~15%) | ~$11,850 |
| Total combined tax | ~$32,850 |
The combined effective rate of approximately ~32.9% exceeds what a sole proprietor or S-Corp owner would pay on the same income. However, C-Corps offer advantages for businesses that retain earnings for growth, have access to certain fringe benefits (like employer-paid health insurance that is fully deductible without income limitations), or plan to go public.
When C-Corp Makes Sense:
- Businesses that reinvest most profits and do not distribute them (the ~21% corporate rate is lower than the top individual rate of ~37%).
- Companies seeking venture capital or planning an IPO.
- Businesses with significant international operations.
- Situations where the qualified small business stock (QSBS) exclusion under Section 1202 applies (up to ~$10 million or ~10x basis of gain excluded from tax on sale of qualifying stock held 5+ years).
Self-Employment Tax: The Hidden Cost
Self-employment tax is the single largest tax surprise for new freelancers and business owners. At ~15.3% on the first ~$176,100 of net earnings (plus ~2.9% Medicare on all additional earnings), it can significantly exceed the federal income tax owed.
Calculating Self-Employment Tax (2026)
| Component | Rate | Wage Base |
|---|---|---|
| Social Security (OASDI) | ~12.4% | First ~$176,100 of net SE earnings |
| Medicare (HI) | ~2.9% | All net SE earnings |
| Additional Medicare Tax | ~0.9% | Net SE earnings above ~$200,000 (single) / ~$250,000 (MFJ) |
Self-employment tax applies to ~92.35% of net self-employment income (the ~7.65% reduction approximates the employer share of FICA that employees do not pay).
SE Tax at Various Income Levels
| Net SE Income | SE Tax | Deductible Half | After-Deduction Cost |
|---|---|---|---|
| ~$30,000 | ~$4,240 | ~$2,120 | ~$2,120 |
| ~$60,000 | ~$8,478 | ~$4,239 | ~$4,239 |
| ~$100,000 | ~$14,130 | ~$7,065 | ~$7,065 |
| ~$150,000 | ~$21,194 | ~$10,597 | ~$10,597 |
| ~$200,000 | ~$27,349 | ~$13,675 | ~$13,675 |
For a comprehensive comparison of independent contractor vs. employee tax treatment, see our 1099 vs. W-2 guide.
Quarterly Estimated Tax Payments
Self-employed individuals, sole proprietors, and partners must make quarterly estimated tax payments to the IRS if they expect to owe ~$1,000 or more in federal tax after credits and withholding.
2026 Quarterly Deadlines
| Quarter | Income Period | Payment Due |
|---|---|---|
| Q1 | January 1 – March 31 | April 15, 2026 |
| Q2 | April 1 – May 31 | June 16, 2026 |
| Q3 | June 1 – August 31 | September 15, 2026 |
| Q4 | September 1 – December 31 | January 15, 2027 |
Safe Harbor Rules
You can avoid underpayment penalties by paying at least:
- ~90% of your current-year tax liability, or
- ~100% of your prior-year tax liability (~110% if prior-year AGI exceeded ~$150,000)
If your income is irregular (common for freelancers and seasonal businesses), you can annualize your income for each quarter rather than paying equal installments. This avoids penalties when most income arrives later in the year.
How to Calculate Estimated Payments
- Project total annual income from all sources.
- Subtract above-the-line deductions and the standard or itemized deduction.
- Calculate income tax on the resulting taxable income.
- Add self-employment tax.
- Subtract credits.
- Divide by 4 for equal quarterly payments, or annualize for uneven income.
- Subtract any tax already withheld from W-2 wages (if you have a day job).
Use our tax bracket calculator to help estimate your liability.
The Most Valuable Business Deductions
The following deductions are the most impactful for small business owners. For a comprehensive list of all deductions, see our complete tax deductions list.
Home Office Deduction
The home office deduction allows you to deduct a portion of your home expenses (rent or mortgage interest, utilities, insurance, maintenance) based on the percentage of your home used exclusively and regularly for business.
- Simplified method: ~$5/sq ft, up to 300 sq ft = ~$1,500 maximum
- Regular method: Actual expenses × business-use percentage. A home office occupying ~200 sq ft in a ~2,000 sq ft home uses ~10% of expenses.
- Example: If your total home costs are ~$30,000/year and your home office is ~10% of your home, the regular-method deduction is ~$3,000.
Vehicle Deduction
Business use of a personal vehicle generates a significant deduction:
- Standard mileage rate: ~$0.70/mile (2026 projected). At ~15,000 business miles per year, this equals a ~$10,500 deduction.
- Actual expense method: Track all vehicle costs (gas, insurance, repairs, depreciation, registration) and multiply by business-use percentage.
- Section 179 for vehicles: SUVs and trucks with a gross vehicle weight above ~6,000 lbs qualify for up to ~$30,500 in first-year Section 179 deduction (2026 projected). Lighter vehicles are subject to luxury auto depreciation limits.
Retirement Plan Contributions
Self-employed retirement contributions are among the most powerful deductions because they reduce both income tax and (for some plans) AGI:
| Plan Type | Maximum Contribution (2026 Projected) | Notes |
|---|---|---|
| SEP-IRA | ~$69,000 (up to ~25% of net SE income) | Simplest to set up; employer-only contributions |
| Solo 401(k) | Allows Roth option; highest limits for lower income | |
| SIMPLE IRA | Lower limits; best for businesses with employees | |
| Defined Benefit Plan | ~$275,000 (varies by age and income) | Highest limits; highest cost to administer |
A self-employed individual earning ~$100,000 who contributes ~$20,000 to a Solo 401(k) reduces their taxable income by ~$20,000, saving approximately $4,400–$7,400 in income tax depending on their bracket, plus a reduction in self-employment tax through the AGI reduction.
Health Insurance Premiums
Self-employed individuals can deduct ~100% of health, dental, and long-term care insurance premiums for themselves, their spouse, and dependents. This is an above-the-line deduction (reduces AGI) and is available even if the taxpayer takes the standard deduction.
For a family paying approximately $1,200–$2,000 per month in health insurance premiums ($14,400–$24,000 per year), this deduction alone saves approximately $3,200–$8,900 in federal taxes.
Qualified Business Income (QBI) Deduction
The ~20% QBI deduction is available to pass-through entity owners (sole proprietors, partners, S-Corp shareholders) on qualified business income.
- Full deduction: Available for taxable income below ~$191,950 (single) or ~$383,900 (MFJ) for 2026 (projected).
- Phaseout for service businesses: The deduction phases out for specified service trades or businesses (law, accounting, consulting, health, financial services, performing arts, athletics) between
$191,950–$241,950 (single) or$383,900–$433,900 (MFJ). - Non-service businesses: Above the threshold, the deduction is limited to the greater of ~50% of W-2 wages paid or ~25% of W-2 wages plus ~2.5% of qualified property.
Example: A sole proprietor consultant earning ~$150,000 in net business income (below the phaseout threshold) receives a QBI deduction of ~$30,000, saving approximately $6,600–$11,100 in federal income tax.
TCJA Sunset Note: The QBI deduction is a TCJA provision scheduled to expire after 2025. If it is not extended, this deduction would not be available for 2026. Monitor legislative developments closely.
Entity Selection Decision Framework
Choose Sole Proprietorship / Single-Member LLC If:
- Net business income is below
$50,000–$60,000 per year - You want the simplest structure with the lowest compliance costs
- The SE tax savings from S-Corp election would not exceed the additional accounting costs (
$1,500–$3,000 per year) - You are testing a new business idea and want minimal overhead
Choose S-Corp Election If:
- Net business income consistently exceeds
$50,000–$60,000 per year - You can pay yourself a reasonable salary and take the remainder as distributions
- The SE tax savings (typically
$2,000–$10,000+ per year) exceed the additional compliance costs - You are a service professional (consultant, freelancer, agency owner) with high margins
Choose Partnership / Multi-Member LLC If:
- You have two or more owners
- You need flexible allocation of income, losses, and deductions
- Partners contribute different amounts of capital, labor, or expertise
Choose C-Corp If:
- You plan to reinvest most profits (take advantage of the ~21% corporate rate)
- You are seeking venture capital or planning an IPO
- You want to take advantage of QSBS exclusion (Section 1202)
- You need certain fringe benefits (fully deductible employer health insurance with no income limitations)
Common Small Business Tax Mistakes
1. Not Separating Personal and Business Finances
Mixing personal and business accounts makes tracking deductions difficult and can jeopardize LLC liability protection. Open a separate business bank account and credit card.
2. Missing Quarterly Estimated Payments
The underpayment penalty for 2026 is approximately ~8% annualized (varies with federal short-term interest rates). Missing all four quarterly payments on ~$20,000 in tax can trigger penalties of approximately $800–$1,200.
3. Setting S-Corp Salary Too Low
The IRS can reclassify distributions as wages if the salary is unreasonably low, triggering back FICA taxes, penalties, and interest. A reasonable salary for a full-time professional in most fields is typically $40,000–$80,000 or more.
4. Failing to Track Mileage
Without a contemporaneous mileage log, the IRS can disallow the entire vehicle deduction. Use a mileage tracking app and record the date, destination, business purpose, and miles for every business trip.
5. Ignoring the QBI Deduction
Many self-employed individuals and their tax preparers fail to claim the ~20% QBI deduction, leaving thousands of dollars on the table. If your taxable income is below the phaseout threshold, the deduction is straightforward.
6. Not Contributing to Retirement Plans
Self-employed retirement contributions (SEP-IRA, Solo 401(k)) are one of the highest-impact deductions available. A ~$25,000 contribution saves approximately $5,500–$9,250 in federal income tax depending on your bracket.
7. Filing as a Sole Prop When S-Corp Would Save Money
The break-even point varies, but many business owners earning ~$60,000+ per year would save money with an S-Corp election. The analysis should compare SE tax savings against additional accounting costs.
State Business Tax Considerations
Business tax obligations vary significantly by state. Some key considerations:
- No state income tax: Texas, Florida, Nevada, Washington, Wyoming, South Dakota, Alaska, and Tennessee impose no state income tax on business income.
- Franchise taxes: Some states impose franchise taxes on businesses regardless of profitability. Texas imposes a margin tax of ~0.375%–~0.75%, and Delaware imposes annual franchise taxes on LLCs and corporations.
- State payroll taxes: States like California impose additional state payroll obligations (State Disability Insurance, Unemployment Insurance, Employment Training Tax).
- Best states for small business taxes: Our best states for small business taxes guide ranks all 50 states based on total business tax burden.
Key Takeaways
- Entity selection is one of the most impactful tax decisions a small business owner makes. The difference between a sole proprietorship and an S-Corp can save
$2,000–$10,000+ per year in self-employment tax at income levels above ~$60,000. - Self-employment tax (~15.3% on the first ~$176,100 of net earnings) is the largest non-income tax for most self-employed individuals. The S-Corp election is the primary tool to reduce it.
- Quarterly estimated tax payments are mandatory for most self-employed individuals who expect to owe ~$1,000+ in tax. Missing payments triggers penalties of approximately ~8% annualized.
- The most valuable business deductions are retirement plan contributions (up to
$69,000), health insurance premiums ($14,400–~$24,000+ per year for families), the home office deduction (up to ~$3,000+ with the regular method), and the QBI deduction (~20% of qualified business income). - C-Corps face double taxation on distributed profits but offer advantages for businesses reinvesting earnings, seeking outside capital, or utilizing the QSBS exclusion.
- Separating business and personal finances, tracking mileage, and maintaining accurate records are foundational requirements for maximizing deductions and surviving an audit.
Next Steps
- Evaluate your entity structure. If you are a sole proprietor earning more than
$50,000–$60,000 per year, run the numbers on S-Corp election. The form (2553) has a deadline of March 15 for the current tax year (or within 75 days of formation for new entities). - Set up quarterly estimated payments. Use IRS Form 1040-ES or the Electronic Federal Tax Payment System (EFTPS) to schedule payments. Our tax bracket calculator can help estimate your liability.
- Maximize retirement contributions. Open a SEP-IRA or Solo 401(k) if you have not already. Contributions can be made until the tax filing deadline (April 15, or October 15 with extension for SEP-IRAs).
- Track every deductible expense. Use accounting software (QuickBooks, FreshBooks, Wave) and maintain receipts. Pay particular attention to home office, vehicle mileage, and professional services.
- Claim the QBI deduction. If your income is below the phaseout threshold, the ~20% deduction is available with minimal complexity.
- Consider your state situation. Review our guides on business tax by state to understand your total state-level obligation.
- Hire a tax professional if your situation involves multiple entities, employees, or complex deductions. The cost (
$500–$3,000 depending on complexity) is itself deductible and often pays for itself many times over. See our guide to hiring a tax professional.