A single-member LLC is the default structure for most solo business owners in the United States, and it remains the right choice for a sizable share of them. But once net income crosses roughly $80,000 to $100,000 per year, the math starts pointing toward an S-Corp election, and by $150,000 it’s almost always the better answer from a pure tax-savings perspective.
The reason this conversation matters now is that the gap between the two structures has widened. Self-employment tax rates haven’t dropped. The qualified business income deduction interacts differently with each entity. Reasonable compensation rules have tightened in some industries. And the long-term savings potential of structuring properly compounds significantly across a career. Firms providing corporate and personal tax services deal with this question constantly because the answer changes as a business grows.
Here’s what the actual numbers look like for a representative case.
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The baseline: single-member LLC
Take a consultant earning $140,000 in net business income with no employees. As a single-member LLC, all of that income flows to Schedule C on the personal return. The owner pays ordinary income tax at the personal bracket plus the full 15.3% self-employment tax on the entire amount.
Self-employment tax breakdown: 12.4% Social Security on the first $168,600 (2024 threshold) plus 2.9% Medicare on everything. The half-deduction for the employer-equivalent portion provides modest relief.
On $140,000 of self-employment income, the SE tax alone runs approximately $19,800. Add federal income tax in the 22-24% marginal bracket on the taxable portion, plus state income tax depending on the state. The combined federal tax bill on that income, before the Section 199A pass-through deduction, lands somewhere around $42,000 to $44,000 federal.
The single-member LLC is administratively simple. No payroll. No separate corporate return. The owner files Schedule C with the personal 1040. Compliance costs are minimal.
The alternative: S-Corp election
The same consultant elects S-Corp status by filing Form 2553. The business is now treated as an S-Corporation for tax purposes, even if the underlying legal entity remains an LLC.
The structural change is significant. The owner becomes an employee of the S-Corp and must pay themselves a reasonable salary through payroll. Payroll taxes apply to that salary. Anything left over after salary and business expenses passes through to the owner as a distribution, which is not subject to self-employment tax.
Let’s say the reasonable salary for a consultant of this caliber, based on industry data and local market norms, is $75,000. The owner runs payroll on that $75,000, which incurs the standard FICA taxes (employer and employee portions, totaling 15.3% on the salary). That’s about $11,500 in payroll taxes on the salary portion.
The remaining $65,000 of business profit (after salary) passes through as a distribution. No self-employment tax on this portion. Federal income tax still applies.
The total tax bill on $140,000 of business income through the S-Corp structure runs approximately $35,000 to $37,000 federal, depending on the state and the exact bracket calculation. The savings versus the single-member LLC: roughly $5,500 to $8,000 per year.
Multiply that across ten or twenty years of a career, and the difference is substantial. Reinvested at modest market returns, the lifetime impact runs into six figures easily.
Where the math flips back
The S-Corp election is not free.
Administrative costs increase. The business must file a separate 1120-S corporate return. Payroll has to run on a quarterly basis at minimum. State filing fees for an S-Corp can exceed those for an LLC. A registered payroll service or in-house payroll setup is required. The total additional compliance cost typically runs $1,500 to $3,500 per year depending on complexity and who handles it.
If business profit is below approximately $50,000, the S-Corp election usually loses money once you account for these compliance costs. Between $50,000 and $80,000, it’s roughly a wash. Above $100,000, the S-Corp pulls clearly ahead. Above $150,000, the math is decisive.
Industries with established reasonable compensation norms (consulting, medical practices, law firms, accounting firms) work cleanly with the S-Corp model. Industries where the owner does most of the value-creating work themselves (real estate agents, sales professionals) face stricter scrutiny on the reasonable compensation calculation, and the IRS has been more aggressive in recent years about challenging artificially low salaries to maximize distribution treatment.
Personal tax interactions
The structure choice also affects personal returns in ways that are easy to miss.
S-Corp owners receive a W-2 from their own company, which simplifies mortgage qualification, makes Social Security earnings tracking cleaner, and allows for clean retirement plan contributions through the corporation. The Solo 401(k) interacts differently with each structure, sometimes favorably and sometimes not, depending on contribution goals.
Health insurance premiums work differently too. Self-employed LLC owners deduct health insurance above the line on the personal return. S-Corp owners run health insurance through the corporation, which gets added back to the W-2 as wages for federal income tax purposes but remains exempt from FICA, then deducted above the line. The net effect is similar but the mechanics differ.
The qualified business income deduction (Section 199A) applies to both structures but interacts differently with each. For service businesses near the phase-out thresholds, the S-Corp’s lower pass-through income (after salary) can actually preserve the deduction in cases where the LLC’s higher Schedule C income would phase it out.
How to actually make the decision
The decision shouldn’t be theoretical. It should be modeled on actual numbers.
A competent advisor will run side-by-side projections for the same income level, factoring in the additional administrative costs, the realistic reasonable compensation figure for the owner’s industry and location, the state tax implications, and any retirement contribution interactions. The output is a concrete annual dollar comparison.
For most one-person service businesses with net income above $100,000, the projection consistently favors the S-Corp election. For businesses below that line, the analysis usually points to the LLC. The crossover varies by industry and state.
Once an S-Corp election is made, reversing it requires waiting five years before electing again. So the decision deserves real analysis rather than a casual recommendation. Run the numbers. Talk through the implementation. Then choose based on what the math actually shows.
The structure also interacts with longer-term planning in ways that matter. Selling the business eventually, bringing on a partner, transitioning to a family member, or restructuring for an exit all play out differently depending on the entity choice you made years earlier. A solo consultant who never plans to scale faces different considerations than a service firm owner who expects to add employees and grow. The right answer is contextual, not formulaic.
