Sole Proprietor, LLC, S-Corp or C-Corp: Choosing a US Business Structure

Start with two questions, not four options

Almost every bad structure decision comes from comparing four labels side by side. That is the wrong frame. There are really only two questions, and they are answered separately.

Question one: is there a legal wall between the business and me? This is decided by whether you form a state-level entity. If you never file anything with your state, you are a sole proprietor and there is no wall — a business debt or a lawsuit reaches your house, your car and your savings. If you form an LLC or a corporation, a wall exists.

Question two: how does the IRS tax the profit? This is decided separately, by your entity's default treatment or by an election you file. The same LLC can be taxed as a sole proprietorship, a partnership, an S-corporation or a C-corporation without changing its legal form at all.

Separating these two questions makes the rest straightforward: choose the entity based on liability and credibility, then choose the tax treatment based on the numbers.

Sole proprietorship: the default you fall into

If you start doing business and file nothing, you are a sole proprietor by default. There is no formation step, no filing fee and no separate tax return — profit and loss go on Schedule C attached to your personal Form 1040, and self-employment tax is calculated on Schedule SE.

You may still need a local business licence, and if you trade under a name that is not your own you will usually need to register a “doing business as” (DBA) name with your county or state. Neither of those creates any liability protection.

What it actually costs you

The absence of a legal wall is not theoretical. If a customer is injured, a supplier sues over an unpaid invoice, or an employee brings a claim, the plaintiff can pursue your personal assets. Business insurance mitigates this but does not replicate it — policies have limits and exclusions, and an entity does not.

There is a second, quieter cost: credibility. Lenders, commercial landlords and larger customers frequently want to contract with an entity. Business credit is difficult to build without one, which matters later when you want financing at a reasonable rate.

A sole proprietorship is defensible for a genuinely low-risk side activity with minimal revenue. As soon as you have employees, physical premises, meaningful contracts or real money moving, the calculus changes.

The LLC: the sensible default

A limited liability company is formed by filing articles of organisation with a state and paying a fee. Ongoing obligations vary widely by state — some charge a modest annual report fee, others levy a substantial franchise tax, so check your specific state before assuming it is cheap.

By default, the IRS does not tax an LLC as a separate thing at all:

• Single-member LLC — treated as a “disregarded entity”. Profit goes on Schedule C, exactly as a sole proprietorship. You still have the legal wall; the tax filing is simply unchanged.
• Multi-member LLC — taxed as a partnership. The LLC files Form 1065 and issues a Schedule K-1 to each member, who reports their share on their personal return.

From either default you can elect corporate treatment: Form 8832 for C-corporation taxation, or Form 2553 for S-corporation taxation.

How owners accidentally destroy their own protection

The legal wall is not permanent. Courts can disregard it — “piercing the corporate veil” — where owners have treated the company as an extension of themselves. The behaviours that invite this are mundane and common:

• Paying personal expenses directly from the business account
• Running business income through a personal account
• Having no operating agreement
• Failing to keep the entity in good standing with the state
• Signing contracts in your own name rather than the company's

Keeping a genuinely separate bank account and paying yourself by deliberate transfer is not bureaucratic fussiness. It is the maintenance that keeps the protection real.

The S-corporation election and what it actually saves

Elect S-corp treatment and the business files its own return (Form 1120-S) and issues K-1s, but pays no federal income tax itself — profit still flows to your personal return. So why bother?

The answer is self-employment tax. As a sole proprietor or default LLC, your entire net profit is subject to it. Under an S-corp, you must pay yourself reasonable compensation as a W-2 employee, and that wage carries payroll tax — but profit distributed above that wage does not.

A worked illustration

Suppose the business nets $120,000 and a defensible market wage for your role is $70,000. As a default LLC, self-employment tax applies to the full net profit. As an S-corp, it applies to the $70,000 wage; the remaining $50,000 comes out as a distribution without self-employment tax.

The self-employment tax rate is [VERIFY: current self-employment tax rate — Social Security + Medicare components, irs.gov], and the Social Security portion applies only up to an annual wage base that changes each year [VERIFY: current Social Security wage base for the tax year, ssa.gov]. Run your own numbers against current figures rather than a rule of thumb.

The costs nobody mentions upfront

The saving is real but it is not free:

• Payroll infrastructure. You must actually run payroll — withholding, deposits, quarterly Form 941, year-end W-2. Typically a few hundred to over a thousand dollars a year for a payroll service.
• A second tax return. Form 1120-S usually costs meaningfully more to prepare than a Schedule C.
• “Reasonable compensation” risk. Set your wage implausibly low to shrink payroll tax and you invite an IRS challenge, with back taxes and penalties. The wage must be defensible against what someone would be paid to do your job.
• State treatment varies. Some states impose their own tax or fee on S-corporations, eroding the federal saving.

Eligibility limits

Not every business can elect S-corp status. It must be a domestic entity, have no more than 100 shareholders, issue only one class of stock, and have only permitted shareholders — broadly individuals who are US citizens or residents, plus certain estates and trusts. Other corporations and partnerships cannot hold shares. If you plan to raise venture capital, these constraints will eventually force a conversion.

The C-corporation: double taxation, and why some accept it

A C-corporation is a separate taxpayer. It files Form 1120 and pays federal corporate income tax at a flat rate [VERIFY: current federal corporate income tax rate, irs.gov]. When it distributes profit as dividends, shareholders pay tax again on their personal returns. That is the double taxation everyone warns about, and it is genuine.

Owners still choose it for specific reasons:

• Retaining earnings. If profit stays in the business to fund growth rather than being distributed, it is taxed once at the corporate rate. For a capital-hungry business, that can beat pass-through treatment at high personal rates.
• Outside investment. Venture investors expect Delaware C-corporations. Preferred stock, option pools and institutional shareholders are incompatible with S-corp constraints.
• Qualified Small Business Stock. Section 1202 can allow shareholders to exclude a substantial portion of gain on qualifying C-corp stock held for at least five years, subject to detailed conditions [VERIFY: current Section 1202 QSBS exclusion percentage, holding period and gain caps, irs.gov]. For a business that may be sold, this is a serious consideration.
• Fringe benefits. Certain benefits are more favourably treated for C-corp employee-owners than for pass-through owners.

For an ordinary operating business that distributes most of its profit to its owner, the C-corporation is usually the wrong answer.

The four side by side

A practical way to decide

Work through it in this order.

1. Does the business carry any real risk? Employees, premises, physical products, client contracts, vehicles. If yes, form an entity. The annual state fee is cheap insurance against a claim that reaches your personal assets.
2. Are you raising outside investment within a few years? If yes, talk to a lawyer about a C-corporation now. Converting later is possible but costs money and creates complications.
3. Otherwise, form an LLC. It is the right answer for the large majority of owner-operated businesses: real protection, modest cost, flexible tax treatment.
4. Revisit the S-corp election annually. Once profit is consistently high, model the actual saving against payroll and accounting costs in your state. Do not elect it on the strength of a rule of thumb you read online.

One further point that applies to every pass-through structure: the qualified business income deduction under Section 199A has historically allowed eligible owners to deduct a portion of pass-through business income. Its availability and terms have been subject to scheduled expiry and legislative change, so confirm its current status before building it into any projection [VERIFY: current status, percentage and income thresholds of the Section 199A QBI deduction — subject to legislative change, irs.gov].

You are not locked in

Owners often stall on this decision as though it were permanent. It is not. Sole proprietors form LLCs every day. LLCs elect S-corp treatment when the numbers justify it. S-corps revoke the election. Companies convert to C-corporations when they raise money.

Each change has cost, timing rules and occasional tax consequences — elections in particular have filing deadlines that are easy to miss — but none of them is a one-way door. The genuinely damaging choice is operating a risky business with no entity at all, because that exposure cannot be fixed retroactively once a claim has already arisen.

Start with protection that matches your risk, keep clean books and a separate bank account, and revisit the tax election each year as the numbers move.

Educational information only. This guide explains how US business finance generally works. It is not financial, tax, investment or legal advice, and it does not account for your circumstances. Tax figures change annually and rules vary by state — anything highlighted for verification must be confirmed against current IRS or state guidance. Consult a qualified professional before acting. See the full disclaimer.