One of the first decisions a new business owner makes, often before the business has its first customer, is which legal entity to form under. It's also one of the decisions most often made carelessly, copied from what a friend did or picked because it sounded simple, without weighing liability protection, tax treatment, or how the choice will affect fundraising or an eventual sale years down the road.
The right entity depends on the specifics of the business: how it's owned, how it makes money, whether it plans to raise outside capital, and what an eventual exit might look like. Here's how the four common structures actually compare.
The Four Structures, Side by Side
| Entity | Liability protection | How it's taxed | Best fit |
|---|---|---|---|
| Sole proprietorship / general partnership | None: owner's personal assets are exposed to business liabilities | Pass-through; profit reported on owner's personal return, subject to self-employment tax | Very early-stage, low-risk businesses testing an idea before formalizing |
| Limited Liability Company (LLC) | Yes, separates personal assets from business liabilities | Pass-through by default; can elect S-corp or C-corp tax treatment | Most small businesses wanting liability protection with tax flexibility |
| S-Corporation | Yes (as a corporation or as an LLC electing S-corp treatment) | Pass-through, but allows a reasonable salary plus distributions to reduce self-employment tax exposure | Profitable owner-operated businesses where the self-employment tax savings outweigh added payroll complexity |
| C-Corporation | Yes | Corporate-level tax on profits; dividends taxed again at the shareholder level ('double taxation') | Businesses planning to raise venture capital, issue multiple share classes, or reinvest most profit rather than distribute it |
Liability: Why This Matters Before Tax Treatment
Before getting to tax mechanics, the more fundamental question is liability. A sole proprietorship or general partnership offers no separation between business and personal assets: if the business is sued or can't pay a debt, the owner's personal assets, home, savings, personal accounts, are exposed. An LLC, S-corporation, or C-corporation creates a legal separation, so a properly maintained entity generally shields personal assets from business liabilities.
Forming an LLC or corporation only protects personal assets if the entity is actually maintained as separate from the owner: separate bank accounts, no commingling of funds, and adherence to the entity's formalities. Courts can and do disregard the entity ("pierce the corporate veil") when an owner treats a formal entity like a personal checking account.
Self-Employment Tax and the S-Corporation Election
For a profitable, owner-operated business, the most consequential tax decision is often whether to elect S-corporation tax treatment.
Default pass-through treatment
A single-member LLC's profit passes through to the owner's personal tax return and is generally subject to self-employment tax on the full amount, covering the equivalent of both the employer and employee shares of Social Security and Medicare taxes.
The S-corp election changes the mechanics
An eligible LLC or corporation can elect S-corporation tax treatment (IRS Form 2553). The owner who works in the business becomes an employee, paid a reasonable salary subject to standard payroll tax.
Remaining profit becomes a distribution
Profit beyond the reasonable salary is distributed to the owner and is generally not subject to self-employment tax, which is where the tax savings potential comes from.
The tradeoff is complexity
S-corp status requires running payroll, filing additional tax forms, and defending the 'reasonable salary' figure to the IRS, which scrutinizes S-corp owners who set their salary artificially low to minimize payroll tax.
The S-corporation election tends to make the most financial sense once a business's profit meaningfully exceeds what a reasonable salary for the owner's role would be, since that's the portion of profit that could otherwise be paid out as a distribution instead of being taxed as self-employment income. Below that threshold, the added payroll and compliance cost can outweigh the tax savings. This is a calculation worth running with an advisor rather than assuming, since it depends on the specific numbers.
The Qualified Business Income (QBI) Deduction
Owners of pass-through entities, sole proprietorships, partnerships, LLCs, and S-corporations, may be eligible for the Qualified Business Income (QBI) deduction under Internal Revenue Code Section 199A, which can allow a deduction of up to 20% of qualified business income, subject to income thresholds and, for certain service businesses, phase-out limits at higher income levels. This deduction is a meaningful factor in comparing the after-tax outcome of pass-through structures against a C-corporation, where no equivalent deduction applies to the corporation itself.
Double Taxation and When a C-Corporation Still Makes Sense
A C-corporation pays corporate income tax on its profits, and if those after-tax profits are distributed to shareholders as dividends, the shareholders pay personal tax on the dividends as well. This is the "double taxation" C-corps are known for, and it's a real cost for a business planning to distribute most of its profit to owners.
| Reason a C-corp still makes sense | Why |
|---|---|
| Raising venture capital | Institutional investors overwhelmingly expect a Delaware C-corporation structure, and S-corp shareholder restrictions are incompatible with most venture investment |
| Multiple classes of stock | C-corps can issue different classes of shares (common, preferred) with different rights, which S-corps cannot do |
| Reinvesting most profit | A business that reinvests earnings rather than distributing them avoids triggering the dividend-level tax until profits are actually paid out |
| Employee equity plans | C-corps offer more flexibility for stock option pools and equity compensation structures common in venture-backed companies |
How the Choice Affects a Future Exit
Entity structure also shapes what an eventual sale looks like. An asset sale versus a stock sale is taxed differently depending on entity type, and buyers often have a strong preference for how a target business is structured, particularly private equity buyers who frequently prefer to acquire assets from a pass-through entity rather than stock, for tax reasons on their side of the transaction. This is a case where getting advice at formation, with an eye toward the kind of exit the business might eventually pursue, avoids costly restructuring later.
- Will the business ever raise outside equity capital, and from whom (angel, venture capital, or self-funded)?
- How much of the business's profit will be distributed to owners versus reinvested?
- Is the owner actively working in the business, and would an S-corp election meaningfully reduce self-employment tax?
- Are there multiple owners, and if so, how will profit-sharing and control be structured?
- What does a likely future sale look like: asset sale, stock sale, or acquisition by private equity?
There's no single "best" entity. An LLC offers flexibility and liability protection for most small businesses. An S-corporation election can meaningfully reduce self-employment tax once profits reach a certain level, at the cost of added compliance. A C-corporation is generally the right call for businesses planning to raise venture capital or reinvest heavily rather than distribute profit. The right choice depends on the specifics of the business, and it's worth getting right at formation rather than restructuring under pressure later.
Not sure which entity fits your business?
SMAART Advisors helps new and growing businesses choose and structure the entity that fits their liability, tax, and fundraising goals, before the paperwork is filed.
Talk to an advisorSources
- IRS.gov: Business Structures
- IRS.gov: S Corporations
- IRS Publication 3402: Taxation of Limited Liability Companies (irs.gov)
- IRS.gov: Qualified Business Income Deduction (Section 199A)
- IRS.gov: Self-Employment Tax (Social Security and Medicare Taxes)
- U.S. Small Business Administration: Choose a business structure (sba.gov)
Frequently asked questions
A single-member LLC taxed by default (a "disregarded entity") has all its profit subject to self-employment tax, currently the Social Security and Medicare taxes an employer and employee would otherwise split. An S-corporation election lets an owner who works in the business take a reasonable salary (subject to payroll tax) and take remaining profit as a distribution that isn't subject to self-employment tax, which can reduce the overall tax bill once profits reach a meaningful level. The tradeoff is more payroll and compliance complexity.
A C-corporation pays corporate income tax on its profits. If it then distributes those after-tax profits to shareholders as dividends, the shareholders pay personal income tax on those dividends again. That's the "double taxation" C-corps are known for. It's a real consideration, but C-corps also have advantages, including no restriction on the number or type of shareholders, which matters for businesses planning to raise venture capital.
Yes, significantly. S-corporations are limited to 100 shareholders, all of whom must be U.S. individuals (with narrow exceptions), which makes them incompatible with most venture capital and institutional investment. C-corporations, particularly Delaware C-corps, are the standard structure venture investors expect. LLCs offer flexibility but can complicate institutional investment due to their partnership-style tax treatment.
In many cases yes, though the process and tax consequences vary. An LLC can elect to be taxed as an S-corporation without changing its legal form. Converting from an LLC to a full C-corporation, or from an S-corp to a C-corp, is more involved and can carry tax consequences. It's generally easier to plan for a likely future structure at formation than to restructure later, which is why the initial choice matters.
