Choosing a business structure means deciding how your company is legally organized and how it is taxed, and in the United States the four options most small owners weigh are the sole proprietorship, the limited liability company (LLC), the C corporation, and the S corporation. The direct answer is this: a sole proprietorship is the simplest to start but gives no personal liability protection; an LLC and a corporation both separate your personal assets from business debts; and an S corporation is not a separate kind of company at all, but a tax election that an eligible LLC or corporation makes with the IRS. Many new small businesses form an LLC for liability protection, then decide separately whether to elect S-corp tax treatment.
This post explains how the four structures compare on liability and taxes, why the S corporation is an election rather than an entity, how pass-through taxation differs from corporate taxation, and the practical questions owners weigh when they choose. It draws on general guidance from the IRS and the U.S. Small Business Administration (SBA), and it is educational information rather than advice for a specific situation.
What are the four main business structures?
The four structures most U.S. small businesses consider are the sole proprietorship, the LLC, the C corporation, and the S corporation, and they differ mainly in liability protection, taxes, and paperwork.
- Sole proprietorship: the default when one person does business without forming a separate legal entity. It is inexpensive and simple, but the owner and the business are treated as the same legal person.
- LLC (limited liability company): an entity created under state law that legally separates the owner's personal assets from the company's debts and obligations. One or more owners, called members, can own it.
- C corporation: a separate legal and tax entity owned by shareholders. It is the default form of corporation and can raise capital by issuing stock.
- S corporation: a corporation or LLC that has asked the IRS to tax it under Subchapter S of the tax code. It is a tax status layered on top of an existing entity.
A general partnership is the multi-owner counterpart to a sole proprietorship and is the default when two or more people run a business together without forming an entity. Like a sole proprietorship, it offers no liability shield.
Is an S corp a business entity or a tax election?
An S corporation is a tax election, not a separate type of legal entity. You first form a legal entity under state law, usually an LLC or a corporation, and then file a form with the IRS to be taxed under Subchapter S.
The mechanics matter. A corporation or an eligible LLC elects S status by filing IRS Form 2553. To qualify, the business generally must:
- Stay within the shareholder limit: an S corporation may have no more than 100 shareholders.
- Have one class of stock: it cannot issue multiple classes with different economic rights.
- Have only eligible owners: shareholders must generally be individuals who are U.S. citizens or residents, plus certain trusts and estates. Partnerships, corporations, and nonresident aliens cannot be shareholders.
Because it is only a tax status, an S corporation still has the underlying liability protection of the LLC or corporation it started as. If you end the S election, the entity itself does not disappear; it simply returns to its default tax treatment.
How does liability protection differ between these structures?
Liability protection depends on whether you have formed a separate legal entity, not on how the business is taxed. This is the single biggest practical reason owners move away from operating as a sole proprietor.
- Sole proprietorship and general partnership: no liability shield. If the business is sued or cannot pay its debts, the owner's personal assets, such as savings, a car, or a home, can be exposed.
- LLC and corporation: limited liability. Creditors of the business can generally reach only business assets, not the owners' personal property.
That protection is not absolute. Owners can still be personally responsible when they sign a personal guarantee on a loan or lease, commit fraud, fail to keep business and personal finances separate (which can let a court "pierce the corporate veil"), or are personally negligent. Keeping a separate bank account, proper records, and adequate insurance helps preserve the shield.
How are LLCs and corporations taxed?
Businesses are taxed in one of two broad ways: pass-through taxation or corporate taxation. Understanding the difference is the key to the LLC-versus-S-corp decision.
Pass-through taxation means the business itself pays no federal income tax. Instead, profits and losses "pass through" to the owners, who report them on their personal returns and pay tax once. Sole proprietorships, partnerships, most LLCs by default, and S corporations are all taxed this way. A single-member LLC is treated as a disregarded entity and reported on the owner's Schedule C by default, while a multi-member LLC is taxed as a partnership.
Corporate taxation applies to a C corporation, which is a separate taxpayer. The corporation pays a flat federal corporate income tax of 21 percent on its profits. When it then distributes profits to shareholders as dividends, those shareholders pay tax again on their personal returns. This two-layer result is often called double taxation.
An LLC is flexible on this point. By default it is a pass-through, but it can elect to be taxed as a C corporation or, if it qualifies, as an S corporation. The legal entity stays the same; only the tax label changes. Self-employment tax is the other piece: sole proprietors and standard LLC members generally pay self-employment tax (Social Security and Medicare, currently 15.3 percent) on the full profit of the business, and an S-corp election can change that.
How do owners choose between an LLC and an S corp election?
Owners usually form an LLC first for liability protection, then consider an S-corp election mainly to reduce self-employment taxes once profits are consistent and meaningful. The two decisions are separate: the LLC is the legal wrapper, and the S election is a tax choice on top of it.
Here is the trade-off. In an S corporation, an owner who works in the business must be paid a "reasonable" salary as a W-2 employee, and payroll taxes apply to that salary. Profit taken above the salary is a distribution that is generally not subject to self-employment tax. When profits are high enough, that split can lower the total tax bill.
Those savings come with added cost and complexity:
- Payroll and compliance: you must run payroll, file employment tax returns, and document reasonable compensation.
- Stricter rules: the shareholder, stock, and eligibility limits above continue to apply.
- Less benefit at low profit: if the business earns little or is not yet profitable, the extra administration can outweigh the tax savings.
There is no single income threshold that fits everyone. A tax professional can run the numbers for your specific profit level and state.
What to do next
A workable sequence for most new owners looks like this:
- Start with liability: decide whether you need a separate entity. If you do, an LLC is a common first step because it is simpler than a full corporation.
- Form the entity correctly: register with your state, get an EIN from the IRS, and keep business finances separate.
- Then decide on tax status: with an accountant, compare default pass-through treatment against an S-corp election based on your actual profit.
- Revisit as you grow: you can change tax treatment later, for example electing S status once profits rise or converting to a C corporation if you seek outside investors.
- Check state rules: some states impose their own franchise taxes, fees, or filing requirements that affect the math.
Business formation and tax rules vary from state to state, and both federal tax law and state entity law change over time. Use this article as a general overview, and confirm the choice that fits your situation with a licensed attorney and a qualified tax professional before you file.