One of the most consequential financial decisions a business owner makes is one that often gets the least deliberate attention: the legal structure of the business. Most people choose a structure when they first form the company, based on whatever their attorney or online incorporation service suggested at the time, and then rarely revisit it.
That is a problem, because the entity structure determines how business income flows to the owner, how it gets taxed, and at what rate. The difference between the wrong structure and the right one can run into tens of thousands of dollars per year for a profitable business. And the right answer changes as the business grows.
This post explains how taxation actually works for the three most common structures; LLC, S-Corp, and C-Corp; and how to think about which one fits your situation.
Most small businesses start as LLCs because they are simple to form, flexible to operate, and offer liability protection without a lot of administrative overhead. But an LLC is a legal structure, not a tax structure. The IRS does not have a separate tax category for LLCs. How an LLC gets taxed depends on how many owners it has and what elections, if any, have been made.
A single-member LLC is taxed as a sole proprietorship by default. All business profit flows directly to the owner’s personal tax return on Schedule C and is subject to both income tax and self-employment tax. Self-employment tax, which covers Social Security and Medicare, runs at 15.3% on the first roughly $185,000 of net earnings and 2.9% on everything above that. For a profitable business, that is a significant additional tax burden on top of ordinary income tax rates.
A multi-member LLC is taxed as a partnership by default. Profit is allocated among the members according to ownership percentage (or as specified in the operating agreement), passes through to their personal returns, and is subject to self-employment tax in the same way.
This default treatment is fine for many businesses, particularly early-stage ones where profits are modest or reinvested. It becomes more expensive as net income grows.
An LLC or a corporation can elect to be taxed as an S-Corp by filing Form 2553 with the IRS. This election does not change the legal structure, an LLC can remain an LLC, but it changes how the income gets taxed in a way that can produce meaningful savings for owners who are actively working in the business.
Here is the core mechanics: under S-Corp taxation, the business is still a pass-through entity. Profit flows to the owners’ personal returns, not to a separate corporate return. No double taxation. But instead of all profit being subject to self-employment tax, S-Corp owners who work in the business are required to pay themselves a reasonable salary. That salary is subject to payroll taxes; Social Security and Medicare; the same as any W-2 employee. The profit above and beyond the salary, distributed to the owner, is not subject to self-employment tax.
The savings come from that distribution. If a business earns $300,000 in net profit and the owner pays themselves a reasonable salary of $120,000, the remaining $180,000 can be distributed without self-employment tax. At 15.3%, that represents roughly $27,000 in potential savings, though the actual number depends on income levels, state taxes, and the specific payroll tax calculation.
The catch is the “reasonable salary” requirement. The IRS scrutinizes S-Corps where owner compensation looks artificially low to maximize distributions. The salary needs to reflect what the market would pay for the owner’s role. Underestimating it to capture more distribution income is an audit risk.
S-Corp status also comes with administrative costs that offset some of the savings: payroll processing, additional tax filings, and more complex accounting. The savings need to exceed those costs for the election to make financial sense, which is why most tax advisors suggest the S-Corp election starts making sense somewhere around $50,000 to $80,000 in consistent annual profit, though the threshold varies.
Getting your accounting properly structured to track salary versus distributions accurately is part of what makes the S-Corp election work in practice. The post on GAAP vs. cash basis accounting explains why the accounting method underlying your books affects how this gets reported.
A C-Corp is taxed as a separate entity from its owners. It files its own tax return and pays corporate income tax on its profits. As of 2018, the federal corporate tax rate is a flat 21%. Owners are then taxed again when they receive dividends, hence the term double taxation.
For most small businesses, double taxation is a significant disadvantage. A business earning $300,000 pays $63,000 in corporate tax first. The remaining $237,000, if distributed as dividends, is taxed again at the owner’s qualified dividend rate, currently 15% to 20% for most taxpayers. Total tax in that scenario is considerably higher than the pass-through treatment of an LLC or S-Corp.
For most small and mid-size businesses, this makes C-Corp status the least attractive option from a pure tax standpoint, unless the business is retaining significant earnings in the corporation rather than distributing them.
The calculus changes in a few specific situations.
If the business is accumulating profits to reinvest in growth rather than distributing them to owners, the 21% corporate rate is lower than the top personal income tax rates, which currently reach 37% for individuals. A business owner in the highest bracket who retains earnings in a C-Corp pays 21% on those retained profits rather than 37% on pass-through income. That difference compounds over time.
If the business plans to raise venture capital or institutional investment, C-Corp is almost always the required structure. Institutional investors, including VCs and most PE firms, cannot hold S-Corp stock due to restrictions on the types of eligible shareholders and classes of stock. LLCs create complications for tax-exempt investors like university endowments and pension funds. C-Corp is the clean answer for any company on a venture-backed trajectory.
If the company plans to offer equity compensation broadly; stock options, RSUs, equity incentive plans; C-Corp structure makes this considerably simpler from both a legal and tax standpoint.
If your business is approaching a fundraise or building toward institutional investment, understanding the cap table and equity structure implications of entity choice belongs in the same conversation as the tax analysis.
LLC (default pass-through): All profit is subject to self-employment tax. Simple and flexible. Works best for early-stage businesses or those with modest, variable profits. No separate corporate tax return.
S-Corp: Profit splits between salary (subject to payroll taxes) and distributions (not subject to self-employment tax). Pass-through taxation, no double taxation. Works best for profitable owner-operated businesses with consistent earnings. Comes with administrative overhead and IRS scrutiny on reasonable salary.
C-Corp: Corporate-level tax at 21% flat rate, then owner-level tax on dividends. Double taxation disadvantage for most small businesses. Works best for companies retaining earnings, raising venture capital, or planning broad equity compensation programs.
Federal taxes are only part of the equation. Once state taxes enter the picture, the math on entity structure can shift considerably and not always in the direction you would expect.
Some states have no income tax at all, which changes the S-Corp vs. LLC calculus significantly. Others layer on franchise taxes, minimum taxes, or entity-level fees that apply regardless of whether the business was profitable that year. California is one of the more expensive examples: S-Corps pay an additional 1.5% tax at the entity level on top of the federal pass-through treatment, and LLCs owe a minimum $800 annual franchise tax even in a breakeven year. For a business owner in California who ran the federal numbers and concluded the S-Corp election was a clear win, the state piece can meaningfully erode that advantage.
Multi-state operations add another dimension entirely. A business with employees, offices, or even just significant sales activity in multiple states may have created a tax nexus in those states without realizing it, which can mean separate registration, filing, and tax payment obligations in each one. The entity type can affect how that nexus is calculated and what obligations follow.
Entity structure decisions should not be permanent defaults. A structure that made sense when the business was generating $80,000 in annual profit may not be optimal at $500,000. A company that started bootstrapped may need to convert to C-Corp when institutional investors enter the picture. A business that brought on a partner may need to change from a single-member LLC.
The right time to review is usually when something significant changes: profit crosses a meaningful threshold, the ownership structure changes, the business plans to raise outside capital, or a major transaction is on the horizon.
Converting from one structure to another is manageable but has tax implications that require careful planning. Converting an LLC to a C-Corp, for example, can trigger recognition of built-in gains. The timing and method of conversion matter. This is not a decision to make without tax and accounting guidance.
When your business reaches the point where entity structure, tax optimization, and financial planning are interconnected decisions, having a fractional CFO or experienced controller in your corner makes a real difference in getting them right.
What is the main difference between S-Corp, C-Corp, and LLC taxation?
An LLC by default passes all income through to the owner’s personal return, with the entire profit subject to self-employment tax. An S-Corp also passes income through but splits it between a required owner salary and distributions, reducing the amount subject to self-employment tax. A C-Corp is taxed as a separate entity at a flat 21% corporate rate, with owners taxed again on dividends, creating double taxation that makes it less attractive for most small businesses unless profits are being retained or the company is raising institutional capital.
At what income level does an S-Corp election make sense?
Most tax advisors put the threshold somewhere between $50,000 and $80,000 in consistent annual net profit, though the right number depends on state taxes, the cost of payroll administration, and what constitutes a reasonable salary for the owner’s role. Below that level, the tax savings may not exceed the additional administrative costs.
Can an LLC be taxed as an S-Corp?
Yes, and this surprises a lot of business owners who assume switching tax treatment requires changing the legal structure entirely. It does not. An LLC can file Form 2553 with the IRS to elect S-Corp tax treatment while remaining an LLC for all legal purposes. The underlying entity does not change, only how the IRS treats the income.
That said, not every LLC qualifies. To be eligible for S-Corp treatment, the business needs to have fewer than 100 shareholders, only one class of stock, and shareholders who meet the IRS’s eligibility rules. Most corporations, partnerships, and non-resident aliens cannot be S-Corp shareholders, so if the ownership structure includes any of those, the election is off the table.
Is a C-Corp better for startups?
It depends almost entirely on where the startup is headed. If venture capital or institutional investment is part of the plan, C-Corp is not just better, it is essentially required. Most institutional investors, including VCs, will not invest in S-Corps or LLCs. S-Corps have shareholder restrictions that disqualify most investment funds. LLCs create tax complications for certain investors like university endowments and pension funds. C-Corp is the structure that keeps all those doors open.
For a bootstrapped startup with no plans for outside investment in the near term, the picture flips. Pass-through taxation through an LLC or S-Corp is almost always more tax-efficient than paying corporate tax and then getting taxed again on dividends. The right answer really comes down to what the growth path looks like.
What is double taxation for C-Corps?
Double taxation refers to corporate income being taxed twice: first at the corporate level when the business earns it, and again at the individual level when it is distributed to shareholders as dividends. The corporate rate is currently 21%. Qualified dividends are taxed at 15% to 20% for most individuals. Combined, the effective rate on distributed C-Corp profits is higher than pass-through taxation for most small business owners.
Can you switch from one entity structure to another?
Yes, but conversions have tax implications that need to be planned carefully. Converting from an LLC to a C-Corp can trigger gain recognition on appreciated assets. Converting from a C-Corp to an S-Corp requires the business to meet S-Corp eligibility requirements and may trigger built-in gains taxes on appreciated assets for up to five years after conversion. The mechanics vary, and the timing matters significantly for the tax outcome.
What is a reasonable salary for an S-Corp owner?
The IRS requires S-Corp owner-employees to pay themselves a salary that is comparable to what the market would pay someone else to perform the same role. There is no fixed formula, but factors include the owner’s duties, industry compensation benchmarks, the profitability of the business, and what comparable businesses pay for similar roles. Taking no salary or a token salary while receiving large distributions is the specific pattern the IRS looks for in S-Corp audits.
Entity structure is not a one-time administrative decision. It is an ongoing tax and financial strategy question that deserves revisiting as the business evolves.
For most profitable owner-operated businesses, the S-Corp election is worth a serious look once consistent annual profits reach the threshold where the self-employment tax savings outweigh the administrative costs. For businesses on a venture-backed trajectory or planning to raise institutional capital, C-Corp is the practical answer regardless of the short-term tax comparison. For early-stage businesses with modest and variable profits, a default LLC is often the most practical place to start.
The structure that saves the most money is not universal. It is the one that fits the specific combination of profitability, ownership, growth plans, and state tax environment that applies to your business right now, with a plan to revisit it when any of those factors changes.
Quadrant provides outsourced accounting, controller, and fractional CFO services to businesses, nonprofits, and PE-backed companies. If you are unsure whether your current entity structure is still the right one for where your business is headed, we would be glad to talk.
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