Sole Prop vs LLC vs S Corp: What Actually Changes Your Taxes

By Tom, CPA · Updated October 27, 2026

Part of: Tax Planning

TL;DR: An LLC alone does not change federal tax. An S corp election can save payroll tax on profit above a reasonable salary, but adds payroll, a separate return and state costs. Profit level decides.

Educational only, not tax, legal, or investment advice. Examples are illustrations, not predictions. Rules and limits change; verify current figures and talk to a qualified professional about your situation.

Somewhere on the internet right now, a person with $11,000 of side-hustle income is forming an LLC, electing S corporation status, and buying a payroll subscription, convinced they have just outsmarted the IRS. They have mainly outsmarted their own bank account. The tax code is 4 million words long; you need about 400 of them to understand how sole proprietorships, LLCs and S corporations are actually taxed, and why the right answer depends mostly on profit, not paperwork.

This comparison covers default taxation for each structure, how an S corporation election works, why reasonable salary is the hinge, a break-even income range, and the admin costs people forget. It is federal-focused, as of Oct 2026. State rules, especially franchise taxes and entity fees, can change the answer.

CPA Warning Label: Entity changes have legal, state and exit consequences beyond federal tax. Model several years, not just one, before filing Form 2553.

Default taxation: the LLC is a costume, not a tax category

An LLC is a state-law legal entity. For federal tax purposes, it has no tax regime of its own. By default:

So "should I get an LLC for taxes?" is usually the wrong question. A single-member LLC by default changes nothing on your federal return. Its real benefits are legal: liability separation (if you respect the formalities and carry insurance) and a cleaner business identity. For rentals, our rental LLC tax myth guide explains why the LLC is not a tax shelter.

How the S corporation election works

An eligible LLC or corporation files Form 2553 to be taxed as an S corporation. Eligibility basics: a domestic entity, no more than 100 shareholders, only allowed shareholder types (generally individuals, certain trusts and estates, not partnerships or nonresident aliens), and one class of stock.

Timing: to be effective for a calendar year, Form 2553 is generally due by the 15th day of the third month of that year (March 15 for most). The IRS offers late-election relief in Rev. Proc. 2013-30 when the requirements are met, which is a common rescue for people who forgot.

Once elected, the owner who works in the business becomes an employee. The business runs payroll, withholds and pays FICA on the owner's salary, and issues a W-2. Remaining profit passes through on a K-1 and is not subject to self-employment tax. That gap, profit above salary that escapes the 15.3%, is the entire tax point.

Reasonable salary is the hinge

An S corporation owner-employee must take reasonable compensation for services before taking distributions. Pay yourself $0 salary and $150,000 of distributions, and the IRS can reclassify distributions as wages, with back payroll taxes, penalties and interest. Courts have repeatedly sided with the IRS when owners paid themselves little or nothing.

"Reasonable" is facts-and-circumstances: what you would have to pay someone else to do your job, considering training, duties, time, and comparable pay in your industry and area. There is no safe "60/40 rule" in the tax code. See our S corp reasonable salary guide for methods.

Salary also interacts with the QBI deduction. S corp salary is not QBI, so a higher salary lowers QBI while above the threshold W-2 wages can support it. The QBI guide covers the tension.

Break-even income

The S corp tax savings are roughly the payroll tax avoided on profit above salary, minus the extra costs. A rough model for 2026:

• Savings ≈ (profit − reasonable salary) × 15.3% × 92.35%, while total earnings are under the $184,500 Social Security wage base. Above the wage base, the savings drop to about 2.9% (plus 0.9% additional Medicare where it applies).
• Costs: payroll service, separate 1120-S preparation, state filing and franchise fees, unemployment insurance on your salary, and your time.

The savings column ignores employer payroll tax deductibility, state taxes and QBI effects, and the assumed salaries are illustrative, not recommendations. Our S corp election break-even guide works this in more detail.

Admin costs and hidden trade-offs

• Payroll: quarterly Form 941, annual W-2/W-3, state withholding and unemployment filings. A payroll service handles it, for a fee.
• Separate return: Form 1120-S is due March 15 for calendar-year S corps. Late filing penalties apply per shareholder per month.
• State fees: some states charge annual LLC or franchise taxes, and some tax S corporations at the entity level. A few states do not recognize S status at all for some purposes.
• Retirement plans: solo 401(k) employer contributions are based on W-2 salary, not total profit. A low salary can shrink retirement contributions.
• Social Security benefits: lower salary means lower earnings credited to your Social Security record.
• Health insurance: more-than-2% shareholders must run premiums through payroll; see the self-employed health insurance guide.
• Getting out: distributing appreciated property from an S corp is a taxable event. Getting in is easy; getting out can cost money.
• Rental real estate: holding rentals in an S corp is usually a mistake; see why rentals and S corps don't mix.

Multi-member LLCs and C corporations

Two or more owners change the picture. A multi-member LLC defaults to partnership taxation: it files Form 1065, issues K-1s, and active members generally pay self-employment tax on their share of trade or business income plus any guaranteed payments. Partnerships are flexible. They can make special allocations of income and loss among partners, and distributing property is generally not taxable the way it is from an S corporation. That flexibility costs complexity, but for businesses holding appreciating assets, partnerships are often preferred over S corps.

The C corporation path is different again. A flat 21% corporate rate sounds attractive, but profits paid out as dividends are taxed again on the owner's return, typically at 15% or 20% plus the 3.8% net investment income tax for high earners. C corps make sense for businesses reinvesting most profits, raising outside capital, or aiming for the Section 1202 small business stock exclusion. They rarely make sense for a solo consultant who spends the profit on rent and groceries.

Spouses who co-own an unincorporated business may be treated as a partnership, or in some cases may elect qualified joint venture status and each file a Schedule C. Community property states have their own rules for spousal LLCs.

Illustration: three paths for one business

Taylor, single, runs a non-SSTB web development business with $120,000 of net profit in 2026, no other income, and lives in a state with no special S corp fees.

• Sole prop or single-member LLC: SE tax ≈ $120,000 × 92.35% × 15.3% ≈ $16,955.
• S corp with $70,000 salary: payroll tax (both halves) ≈ $70,000 × 15.3% = $10,710. Payroll tax avoided ≈ $6,245 before costs.
• Costs: suppose $2,500 a year for payroll service, 1120-S preparation and state filings.
• Net estimated benefit: roughly $3,700 a year, before QBI and income tax differences, which shift because salary and the half-SE deduction differ.

If Taylor's profit were $45,000 and a reasonable salary were $35,000, the payroll tax avoided would be about $1,000 (roughly $6,360 of SE tax versus $5,355 of payroll tax), mostly eaten by costs. These are illustrations with assumed salaries, not advice on what Taylor's salary should be.

A simple decision path

1. Is the business consistently profitable? If profit is small or volatile, stay a sole prop or single-member LLC.
2. Do you want liability separation? Form an LLC for legal reasons, and keep insurance. Taxes stay the same by default.
3. Is profit comfortably above a reasonable salary plus admin costs? Model the S corp election with real state costs.
4. Are you near the QBI threshold or an SSTB? Model QBI with and without the election.
5. Revisit every year. An S election that made sense at $150,000 profit may not make sense at $50,000.