Choosing a business structure is really choosing a tax regime — and the wrong choice can cost you thousands every year. A sole proprietorship, an LLC, and a corporation are taxed under fundamentally different rules: who pays, at what rates, and how many times the same dollar gets taxed. This guide compares the tax differences between sole proprietorships, LLCs, and corporations so you can choose the structure that keeps the most of what you earn.
Table of Contents
- The Three Structures at a Glance
- Sole Proprietorship Taxation
- LLC Taxation: Flexibility Is the Point
- Corporation Taxation: C Corps and Double Tax
- The S Corporation Election: A Fourth Path
- Which Structure Saves You the Most?
- Key Takeaways
The Three Structures at a Glance
| Feature | Sole Proprietorship | LLC | Corporation (C Corp) |
|---|---|---|---|
| Separate legal entity | No | Yes | Yes |
| Owner liability protection | None | Yes | Yes |
| Default federal taxation | Pass-through (Schedule C) | Pass-through (disregarded or partnership) | Corporate tax + shareholder tax |
| Self-employment tax | Yes, on all net profit | Yes, by default | No (owners are employees) |
| Can elect S corp taxation | No | Yes | Yes (if eligible) |
| Best for | Testing an idea, solo freelancers | Most small businesses | Businesses seeking outside investors |
The table’s key insight: taxation follows the entity’s tax classification, not just its legal form. An LLC is a legal creature of state law; for federal taxes, the IRS lets it be taxed as a disregarded entity, a partnership, or — by election — as a corporation. Understanding that legal structure and tax structure are separate choices unlocks the real planning opportunities.
Sole Proprietorship Taxation
A sole proprietorship is not taxed at all as a business — you are the business. All profit flows directly onto your personal return via Schedule C, where it is taxed at your individual income-tax rates. There is no separate business return, no corporate rate, and no distinction between “business money” and “your money” in the IRS’s eyes. Simplicity is the entire appeal: one extra form, minimal compliance cost.
The sting is self-employment tax. Because you are both employer and employee, you pay Social Security and Medicare taxes — currently 15.3 percent on the first chunk of net earnings up to the Social Security wage base, then 2.9 percent Medicare beyond it (plus an additional Medicare surtax at high incomes) — on essentially all net profit. A freelancer netting $120,000 pays income tax plus roughly $18,000 in self-employment tax. That burden, more than any other factor, drives profitable sole proprietors toward LLCs with S corporation elections.
Sole proprietors can deduct ordinary and necessary business expenses — home office, mileage, supplies, health insurance premiums (subject to limits) — which reduces both income and self-employment tax. Estimated quarterly payments are required since no employer withholds for you; underpayment penalties surprise many first-year freelancers. Guidance on these obligations is published on irs.gov.
LLC Taxation: Flexibility Is the Point
By default, a single-member LLC is a “disregarded entity” — taxed exactly like a sole proprietorship, with profit on Schedule C and full self-employment tax. A multi-member LLC defaults to partnership taxation: the LLC files an informational return, and each member pays tax on their share via Schedule K-1 at individual rates. In both defaults, the LLC’s liability shield does not change the tax math at all — a fact that surprises owners who assumed “LLC” meant “tax break.”
The LLC’s tax power comes from elections. An LLC can elect to be taxed as an S corporation or a C corporation by filing the appropriate IRS form. The S election is the famous one: owners become employees paid a “reasonable salary” (subject to payroll taxes), while remaining profit flows through free of self-employment tax. For a profitable service business, that election alone can save five figures annually — which is why the S corp vs. C corp comparison matters even to businesses that started as LLCs.
LLCs also offer planning flexibility partnerships-style: special allocations of profit and loss among members (within IRS rules), easier admission of new owners than a sole proprietorship, and basis adjustments that corporations cannot match. The trade-off is complexity and cost — state filing fees, annual reports, and often a CPA to manage the elections correctly. For side businesses with modest profit, the default taxation may be perfectly fine until earnings justify the machinery.
Corporation Taxation: C Corps and Double Tax
A C corporation is a separate taxpayer. It pays federal corporate income tax on its profits — currently a flat 21 percent — and then shareholders pay tax again when profits are distributed as dividends. This “double taxation” is the C corp’s defining drawback: $100,000 of profit can face corporate tax and then dividend tax before the owner spends a dollar of it. Retained earnings left in the company avoid the second layer, which is why growth companies that reinvest everything tolerate the structure.
Owners who work in the business are employees: the corporation pays them salaries (deductible to the corporation, subject to payroll tax like any wages), and can offer fringe benefits — health insurance, retirement plans, group life — with tax advantages often unavailable to the self-employed. For high-earning owners, deductible benefits plus the flat 21 percent rate on retained profits can outweigh double taxation in specific scenarios.
C corps also unlock the investment world: unlimited shareholders, multiple stock classes, and straightforward equity compensation make them the required structure for venture capital and eventual IPOs. No serious startup raises institutional money as an LLC. But for a profitable small business distributing most earnings to its owner, the C corp is usually the most expensive tax choice of the three — a conclusion worth validating against entity-level tax planning before committing.
The S Corporation Election: A Fourth Path
An S corporation is not a different entity type — it is a tax election available to eligible corporations and LLCs. S corps are pass-through: no corporate-level tax, with profit flowing to owners’ personal returns. The magic is payroll: only the owners’ salaries face Social Security and Medicare taxes, while distributed profit escapes them. The IRS requires owner-employee salaries to be “reasonable” for the work performed — you cannot pay yourself $20,000 on $300,000 of profit — but within that guardrail, the savings are real and legal.
Eligibility has strings: 100 or fewer shareholders, all U.S. individuals or qualifying entities (no partnerships or corporations as owners), one class of stock, and no nonresident alien shareholders. These limits rule out most venture-backed companies but fit the vast majority of small businesses. The election itself is made on Form 2553, ideally early in the tax year, and late elections have relief procedures.
The break-even math matters: S corps add payroll processing, a separate business tax return, and stricter bookkeeping. For profits under roughly $40,000–$50,000, the self-employment tax savings may not cover the added costs. Above that range, the election typically pays for itself many times over — which is why accountants raise it with nearly every profitable LLC owner they meet. State tax treatment varies, so confirm your state’s rules on sba.gov state guides or your state’s revenue site.
Which Structure Saves You the Most?
For most solo founders starting out, the practical sequence is: begin as a sole proprietorship (or single-member LLC for liability protection) with default taxation, then elect S corporation taxation once consistent profits exceed the break-even threshold. This path minimizes early complexity while capturing the biggest available tax saving at exactly the point it becomes worthwhile.
Choose C corporation taxation when you plan to raise outside capital, issue equity to many employees, or retain most earnings for growth at the 21 percent rate. Choose partnership-style LLC taxation when multiple owners need flexible profit splits that S corp rules prohibit. And revisit the choice as circumstances change — entity taxation is not a tattoo. Conversions and elections are possible, though each carries its own tax consequences that deserve professional advice.
Two final cautions. First, state taxes and fees can flip the federal math: some states impose entity-level taxes, minimum franchise taxes, or steep LLC fees that change the answer. Second, liability protection is a legal question, not a tax one — never choose a sole proprietorship to save on taxes if your business exposes you to meaningful lawsuit risk. The cheapest structure is the one that keeps both the IRS and the plaintiffs’ bar at bay, a balance that small-business policy debates continually revisit.
