How Your Business Structure Affects Your Taxes

The legal structure you choose for your business is one of the most consequential tax decisions you will make. Whether you operate as a sole proprietor, form an LLC, elect S-Corp status, or incorporate as a C-Corp, each entity type carries different tax rules, rates, and filing requirements. Choosing the wrong structure can mean paying thousands more in taxes than necessary.

Sole Proprietorship: The Default Structure

If you earn money from a business and have not formed a legal entity, the IRS considers you a sole proprietor. All business income and expenses flow through your personal tax return on Schedule C. You pay self-employment tax of 15.3 percent on net earnings in addition to regular income tax. There is no separation between you and the business for tax purposes.

LLC: Flexibility Without Complexity

A limited liability company provides legal protection for your personal assets while offering tax flexibility. By default, a single-member LLC is taxed as a sole proprietorship and a multi-member LLC is taxed as a partnership. However, an LLC can elect to be taxed as an S-Corp or C-Corp if that saves money. This flexibility makes the LLC the most popular structure for small businesses.

S-Corp: Reducing Self-Employment Tax

An S-Corp passes income through to shareholders, but with an important distinction. Owners who work in the business must pay themselves a reasonable salary, which is subject to FICA taxes. Any remaining profit can be distributed as dividends, which are not subject to self-employment tax. For profitable businesses, this salary-plus-distribution strategy can save significant money on payroll taxes.

• Pass-through taxation avoids double taxation
• Reasonable salary requirement enforced by IRS
• Distributions above salary avoid FICA taxes
• Limited to 100 shareholders, all must be US persons
• QBI deduction may apply to pass-through income

C-Corp: Double Taxation but Lower Rates

A C-Corp pays its own income tax at a flat 21 percent federal rate. When profits are distributed as dividends, shareholders pay tax again at their individual rate. This double taxation is the main drawback. However, C-Corps offer advantages like retaining earnings at the 21 percent rate, broader fringe benefit deductions, and no restrictions on ownership structure. Tech startups often choose C-Corp status for these reasons and for venture capital compatibility.

Making the Right Choice

The best structure depends on your income level, growth plans, and how you plan to use profits. Sole proprietorships work well for low-revenue side businesses. LLCs suit most small businesses. S-Corp election makes sense when net income consistently exceeds 50,000 to 60,000 dollars. C-Corps are best for businesses seeking outside investment or planning to retain significant earnings. Consult a tax professional before making structural changes, as some elections are difficult to reverse.

References

• IRS: Business Structures (irs.gov/businesses/small-businesses-self-employed/business-structures)
• IRS: S Corporations (irs.gov/businesses/small-businesses-self-employed/s-corporations)
• SBA: Choose a Business Structure (sba.gov/business-guide/launch-your-business/choose-business-structure)

Key Takeaways

• Sole proprietorships and single-member LLCs default to Schedule C — income flows to your 1040 and owes 15.3% self-employment tax.
• S-corps split owner pay into 'reasonable salary' (subject to FICA) and distributions (not), saving FICA on the distribution portion.
• C-corps pay a flat 21% federal rate plus shareholder-level tax on dividends — classic double taxation, but useful for retained earnings.
• Partnerships and multi-member LLCs file Form 1065 and pass income to partners via K-1s, with at-risk and passive loss rules applied personally.
• State-level entity choice matters: California charges $800 minimum franchise tax; Delaware requires an annual report; some states tax S-corps.

Common Mistakes to Avoid

• Electing S-corp status too early — the payroll and accounting costs can exceed FICA savings below ~$40–60k of net profit.
• Paying an S-corp owner $0 or an unreasonably low salary; the IRS can recharacterize distributions as wages with penalties.
• Leaving profit in a C-corp indefinitely and hitting the accumulated earnings tax if there's no business reason for the retention.
• Missing the 2553 election deadline (75 days from incorporation or before March 15) and waiting another year for S-corp status.
• Forgetting that LLC does not equal tax entity — an LLC is a legal structure that can be taxed four different ways.

Lina's Decision Tree: Sole Prop vs LLC vs S-Corp at $220K

Lina H. is a single filer in California running a design agency netting $220,000 of profit in 2025. She currently operates as a single-member LLC (taxed as sole prop by default) and is weighing whether to elect S-Corp tax status. The difference at her income level is roughly $11,000 per year in combined federal tax — but comes with added payroll and compliance costs.

• Sole prop / default LLC at $220K profit: full $220K subject to SE tax (up to SS cap) ≈ $24,150
• S-Corp election with $110K reasonable salary + $110K distributions
• SE-equivalent payroll tax on S-Corp salary only: $110K × 15.3% = $16,830
• SE tax savings on distributions (not subject to FICA): $7,320
• S-Corp added costs: ~$1,200/year payroll processing, ~$900/year additional tax prep, $800 state fee in CA
• Net S-Corp savings after added costs: ~$4,420/year
• California-specific caveat: $800 annual franchise tax plus 1.5% S-Corp tax on net income

The S-Corp election is the single most popular tax-driven business-structure move among solo professionals between $100K and $400K of profit. Below ~$80K the added compliance cost eats all the savings; above ~$400K other considerations (QBI phase-outs, multi-state sourcing) dominate. Lina's state matters a lot: California's $800 franchise tax and 1.5% S-Corp tax shrinks the benefit vs the same decision in Texas or Florida.

Worked Example: Selene H. Compares Sole Prop, LLC, and S-Corp

Selene H., single in California netting $130,000, modeled her three structure options. Structure does not change income - it changes how that income is taxed. At $130,000 profit, the S-Corp election typically starts paying off after factoring in payroll costs.

• Sole prop or single-member LLC: entire $130,000 subject to SE tax (minus employer-half deduction). SE tax: roughly $16,700.
• S-Corp election: reasonable salary $70,000 (FICA 7.65% ee plus 7.65% er = roughly $10,700); remaining $60,000 flows through as distribution (no SE tax). Savings: roughly $6,000.
• S-Corp cost: payroll software ($600), separate return Form 1120-S ($900 CPA), CA S-Corp franchise tax ($800 min).
• Net S-Corp benefit at $130,000 profit: roughly $3,700 per year.
• QBI deduction (Section 199A) applies to both structures, with different mechanics - runs through Form 8995.

Selene's S-Corp election nets roughly $3,700 after costs. Below $60,000 to $80,000 of net, the S-Corp overhead usually eats the savings. Reasonable compensation is not optional - Rev. Rul. 59-221 and numerous tax court cases require a fair salary. Publication 542 covers entity tax overview; an S-Corp election uses Form 2553.