By Adam Morris, CPA • September 4, 2025

LLC vs. S Corp vs. C Corp: Tax and Legal Implications

These labels get thrown around like they're "better" or "worse." The truth: each structure is a tradeoff between tax treatment, payroll rules, compliance burden, and how you plan to grow. There is no universally correct answer. The right choice depends on your profit level, how you pay yourself, your ownership plans, and how much administrative complexity you're willing to manage.

Start with the basics: legal structure vs. tax classification

The most common source of confusion is treating "LLC" and "S corp" as the same type of thing. They are not.

An LLC is a legal entity created under state law. It governs liability protection, ownership structure, and operating rules. But how an LLC is taxed is a separate question entirely -- determined by a federal election (or default rules if no election is made).

• A single-member LLC with no election is taxed as a disregarded entity (Schedule C on your personal return -- same as a sole proprietor).
• A multi-member LLC with no election is taxed as a partnership (Form 1065).
• An LLC can elect to be taxed as an S corporation by filing Form 2553.
• An LLC can even elect to be taxed as a C corporation by filing Form 8832.

The entity name does not dictate which tax return you file. Understanding this separation is the foundation of any entity decision.

LLC: what it actually means in practice

For most small business owners, forming an LLC is a reasonable starting point. Formation is typically straightforward: Articles of Organization filed with your state, a modest filing fee (Idaho's filing fee is approximately $100), and an operating agreement documenting ownership and rules.

In its default tax treatment (disregarded or partnership), an LLC passes all income to owners who report it on their personal returns. All net profit (above a $400 minimum) is subject to self-employment tax — 15.3% on the first $184,500 of net earnings (the Social Security wage base for tax year 2026) and 2.9% Medicare above that, plus an additional 0.9% Medicare surtax on net earnings above the high-income thresholds ($200,000 single / $250,000 married filing jointly / $125,000 married filing separately). This is the mechanic that eventually makes an S corp election worth examining as profit grows.

LLCs work well when:

• You're early-stage and want simplicity
• Profit levels don't yet justify the added compliance of an S corp
• You hold real estate or assets where pass-through treatment and flexible ownership matter
• Your income is variable and you want maximum flexibility

S corporation: the tradeoffs

An S corp is not a separate legal entity type -- it is a tax election. A corporation or eligible LLC can elect S corp status by filing Form 2553 with the IRS. The election must meet certain requirements: no more than 100 shareholders, all shareholders must be U.S. citizens or permanent residents, and only one class of stock is permitted.

The core mechanic: owner-employees of an S corp must pay themselves a "reasonable salary" via W-2 payroll. Any remaining profit passes through to the owner as a distribution -- and distributions are not subject to self-employment tax. This difference can produce meaningful tax savings when net profit is high enough.

But the S corp is not free. The additional costs and complexity include:

• Running payroll (and paying payroll taxes on the salary portion)
• Filing a separate S corp return (Form 1120-S) in addition to your personal return
• Potentially increased CPA fees for the additional complexity
• Maintaining a payroll service year-round
• State-level filing and reporting requirements

Whether the SE tax savings exceed these added costs depends heavily on your profit level. As a planning-screen rule of thumb, the math often starts to favor an S corp election somewhere in the $40,000 to $80,000-plus range of annual net profit — but this is a starting point for the conversation, not a fixed threshold. The actual decision depends on your reasonable-compensation salary, your state, the cost of running payroll and an additional return, and how much profit-splitting room exists at your income level. Your CPA can model the breakeven for your situation.

The reasonable compensation requirement is not optional. The IRS does scrutinize S corp returns where owners pay themselves little or no salary while taking large distributions. Getting this wrong creates payroll tax liability plus penalties. What counts as "reasonable" depends on industry, role, and what the market would pay for similar work.

C corporation: when it actually applies

A C corporation is a separate taxpaying entity. It files Form 1120 and pays its own federal tax at a flat 21% rate. Profits distributed to shareholders as dividends are taxed again at the shareholder level -- this is the "double taxation" you've probably heard about.

Double taxation is a real cost, so C corps are not the right fit for most small businesses distributing profits regularly. Where C corps tend to make sense:

• Businesses reinvesting most profits into growth -- if you're not taking distributions, there's no second layer of tax immediately.
• VC-backed or investment-track businesses -- investors almost always require a C corp structure, and Delaware C corps are the standard.
• Qualified Small Business Stock (IRC Section 1202): QSBS is C-corp-only, which makes it one of the legitimate reasons to pick — or switch to — a C corp when the long-term plan is a stock sale.¹ The 2025 tax legislation restructured the rules in two directions.² For QSBS acquired on or after July 5, 2025, the exclusion now tiers with holding period (50% at 3 years, 75% at 4 years, 100% at 5 years), the per-issuer cap moves up to $15 million (indexed), and the issuer gross-asset threshold is higher. For QSBS acquired on or before July 4, 2025, the legacy rules still apply — 100% exclusion at 5 years, $10 million cap. For founders weighing entity structure against a potential future sale, §1202 is often the specific reason a C corp earns a look.
• Specific benefit structures -- certain employee benefit arrangements work differently in a C corp context.

C corps carry the highest compliance burden: a separate federal return, potential state filings, corporate governance requirements, and more complex planning. The added cost is typically justified by the strategic reasons above, not by operational simplicity.

The practical decision framework

When evaluating entity structure, start with these questions:

• What is your profit trajectory? Low-profit businesses rarely benefit from S corp complexity. High-profit businesses should model it carefully.
• Will you reinvest or distribute earnings? Regular distributions favor pass-through treatment. Reinvestment-heavy businesses may find C corp rates attractive.
• How complex is your ownership? Multiple owners, foreign owners, or equity plans may rule out S corp eligibility.
• What is your compliance tolerance? S corp and C corp both add administrative overhead. Weigh that against potential savings.
• Are you planning a sale? Exit strategy can affect entity preference significantly.

This decision also doesn't have to be permanent -- many businesses start as LLCs and make an S corp election later as profit grows. Planning the transition is easier than doing it reactively. See Choosing the Right Entity Structure for a broader framework, and pair it with Tax Planning Strategies for Small Businesses.

Common mistakes

• Treating entity choice as "set it and forget it." As your business grows or changes, the optimal structure can shift. Review it at major milestones.
• Ignoring payroll and bookkeeping requirements. An S corp without proper payroll is a compliance liability, not a tax strategy.
• Letting the internet decide. "My friend saved $20,000 with an S corp" is not a substitute for modeling your specific numbers.
• Conflating legal protection with tax planning. An LLC provides liability protection (with proper setup); how it's taxed is a separate conversation.

When to get help

If your profit is growing, you're adding owners, planning a sale, or you want a forward-looking view of your entity strategy, this is exactly the kind of decision that benefits from an advisor who knows your numbers. Use KPIs for Business Health to keep your growth metrics clear before the conversation.

FAQs

• Can an LLC be taxed as an S corp? Yes, by filing Form 2553, if the LLC meets eligibility requirements. This is one of the most common planning moves for growing businesses.
• What is "reasonable compensation"? A salary the market would pay for the services you perform for the business. The IRS compares it to industry data and what you'd pay a third-party employee doing the same job.
• Will an S corp always reduce taxes? No. The savings depend on your profit level, salary requirement, and the added compliance costs. Below certain profit thresholds, the math often does not favor an S corp.
• What if I reinvest profits? If you're keeping profits in the business rather than distributing them, the C corp flat rate may be worth modeling alongside S corp pass-through rates.
• How often should I revisit my entity choice? At major changes: significant profit growth, adding or removing owners, preparing for financing, or planning an exit.