Data Notice: Tax rates, filing requirements, and entity rules cited in this article reflect projected 2026 figures. Business formation rules vary by state. Consult a qualified tax professional and attorney before choosing a business entity.

Starting a Business: LLC vs S-Corp vs Sole Prop — Entity and Tax Guide

Your choice of business entity determines how much you pay in taxes, how much personal liability you carry, and how much paperwork you do every year. The wrong structure can cost you $10,000+/year in unnecessary self-employment tax. The right structure at the wrong time creates administrative overhead that outweighs the savings. This guide compares every common entity type with specific income thresholds for when to switch.

Entity Comparison at a Glance

Feature	Sole Proprietorship	Single-Member LLC	S Corporation	C Corporation
Formation cost	$0	$50 - $500 (state filing)	$50 - $500 + S election	$50 - $500
Liability protection	None	Yes	Yes	Yes
Self-employment tax	Yes (15.3%)	Yes (15.3%)*	On salary only	None (but double taxation)
Tax filing	Schedule C (personal return)	Schedule C (default)	Form 1120-S + Schedule K-1	Form 1120
QBI deduction (Section 199A)	Yes	Yes	Yes	No
Ease of use	Simplest	Simple	Moderate	Complex
Best for	Side hustles, testing a business	Freelancers under ~$60K profit	Service businesses over ~$60K-80K profit	Venture-backed startups, reinvesting profits

*A single-member LLC is a “disregarded entity” for federal tax purposes — it is taxed identically to a sole proprietorship unless you elect S-corp treatment.

Sole Proprietorship: The Default

If you freelance, consult, or operate any business without forming a legal entity, you are a sole proprietor by default. All business income flows to Schedule C on your personal tax return.

Advantages:

Zero formation cost or paperwork
No separate tax return
Full QBI deduction eligibility

Disadvantages:

No liability protection — personal assets are exposed to business debts and lawsuits
Full self-employment tax on all net profit (15.3% on first approximately $176,100, then 2.9-3.8% above)
Cannot bring on equity partners

When to use: Testing a business idea, side hustles earning under $10,000/year, minimal liability exposure.

Single-Member LLC: Liability Protection Without Complexity

An LLC provides liability protection (separating personal assets from business debts) without changing your tax treatment. Federally, a single-member LLC is taxed as a sole proprietorship unless you elect otherwise.

Key benefit: If your business is sued or defaults on a debt, only business assets are at risk — not your home, savings, or personal investments.

Formation: File Articles of Organization with your state. Cost: $50-$500 depending on state. Annual fees: $0-$800 (California charges $800/year for all LLCs).

When to use: Any freelancer or solo business owner who wants liability protection but earns under approximately $60,000-$80,000 in net profit.

S Corporation: The Self-Employment Tax Play

An S corporation (or S-corp election on an existing LLC) is the most impactful tax structure for profitable service businesses. It splits your income into salary (subject to FICA) and distributions (not subject to FICA), potentially saving $10,000-$30,000+/year.

How it works:

You elect S-corp treatment by filing Form 2553 with the IRS (deadline: March 15 for current year, or within 2 months and 15 days of formation)
You pay yourself a “reasonable salary” and run payroll
Remaining profit passes through as a distribution, exempt from self-employment tax

Example at $150,000 net profit:

Structure	SE Tax / FICA	Income Tax (est. 22%)	Total Tax
Sole prop / LLC	~$21,200 (SE)	~$33,000	~$54,200
S-corp ($70K salary)	~$10,710 (FICA)	~$33,000	~$43,710
Annual savings			~$10,490

Additional S-corp costs: Payroll service ($500-$2,000/year), separate tax return preparation ($500-$2,000), potentially higher state fees, and reasonable compensation documentation.

The breakeven: S-corp tax savings typically exceed additional costs when net profit consistently exceeds approximately $60,000-$80,000. Below this threshold, the administrative overhead eats the savings.

For detailed self-employment tax reduction strategies, see Self-Employment Tax Strategies.

Source: IRS — S Corporations

C Corporation: For Venture-Backed and High-Growth Businesses

C corporations are taxed separately from their owners at a flat 21% corporate rate. Profits distributed as dividends are taxed again at the shareholder level (qualified dividends at 0/15/20%) — the “double taxation” problem.

When a C-corp makes sense:

Venture capital funding (investors require C-corp structure)
Planning to go public
Retaining significant earnings in the business (21% corporate rate is lower than the top individual rate of 37%)
Qualifying for the Section 1202 QSBS exclusion (up to $10 million in tax-free capital gains on stock held 5+ years)

When a C-corp does not make sense:

Owner-operated service businesses that distribute most profits
Businesses with fewer than $500,000 in retained earnings
Solo entrepreneurs seeking simplicity

Estimated Tax Payments: Do Not Get Caught

Self-employed individuals and S-corp shareholders receiving distributions must make quarterly estimated tax payments. Missing payments triggers underpayment penalties.

Payment	Due Date
Q1	April 15
Q2	June 15
Q3	September 15
Q4	January 15 (following year)

Safe harbor: Pay 100% of last year’s total tax liability (110% if AGI exceeds $150,000) through withholding and estimated payments to avoid penalties, regardless of how much you owe for the current year.

Source: IRS — Estimated Taxes

Choosing Your Entity: The Decision Framework

Your Situation	Recommended Entity
Side hustle, under $10K profit	Sole proprietorship
Freelancer, under $60K profit	LLC (sole proprietorship taxation)
Service business, $60K-$500K profit	LLC with S-corp election
Multiple owners, equal partnership	Multi-member LLC
Seeking venture capital	C corporation
Real estate investing	LLC (separate LLC per property)
Planning IPO in 3-5 years	C corporation

You can change later. Start simple (sole prop or LLC) and upgrade to S-corp when profits justify the complexity. Converting an LLC to S-corp status requires only Form 2553 — no new entity needed.

Retirement Plans for New Business Owners

Opening a retirement plan is one of the first financial moves after forming a business. The options:

Plan	Max Contribution (2026)	Best For
SEP IRA	Up to 25% of net SE income, max ~$70,000	Simple setup, higher income
Solo 401(k)	~$23,500 employee + 25% employer, max ~$70,000	Lower income (higher contribution at same income)
SIMPLE IRA	~$16,500 + 3% match	Small employers with staff

See Tax-Advantaged Accounts Ranked for the full contribution hierarchy.

Key Tax Deductions for New Businesses

Deduction	Details
Startup costs	Up to $5,000 deductible in year 1; remainder amortized over 15 years
Home office	$5/sq ft (simplified, up to $1,500) or actual expenses
Health insurance	100% deductible for self-employed (above-the-line)
Vehicle	~$0.70/mile (standard mileage) or actual expenses
Equipment	Section 179 deduction up to ~$1,250,000; 60% bonus depreciation (phasing down from 100%)
Professional services	Legal, accounting, consulting fees
Business insurance	General liability, E&O, professional liability

Key Takeaways

A single-member LLC is taxed identically to a sole proprietorship but provides liability protection — form one as soon as you have clients or revenue
The S-corp election saves approximately $10,000-$30,000/year in self-employment tax for service businesses with net profit above approximately $60,000-$80,000
C corporations are appropriate for venture-backed startups, companies retaining significant earnings, and those seeking QSBS tax exclusion
Make quarterly estimated tax payments to avoid underpayment penalties — use the safe harbor of 100% (or 110%) of prior-year tax liability
Start simple and upgrade your entity as profits grow — converting an LLC to S-corp requires only a Form 2553 filing

Next Steps

Read Self-Employment Tax Strategies for the full SE tax reduction playbook
See Tax-Advantaged Accounts Ranked for retirement plan setup priorities
Explore Tax Planning Strategies for the broader playbook
Hire a Tax Professional for entity selection advice specific to your business

This content is for educational purposes only and does not constitute financial, tax, or legal advice. Business formation and tax planning depend on your specific circumstances and state of operation. Consult a licensed attorney and tax professional.

Sources

IRS — S Corporations — accessed April 2026
IRS — Estimated Taxes — accessed April 2026
IRS — Business Structures — accessed April 2026
SBA — Choose a Business Structure — accessed April 2026
IRS — Qualified Business Income Deduction — accessed April 2026