Every profitable business owner eventually hears some version of the same advice, usually at a backyard barbecue or in a Facebook group: “You need to be an S corp. It’ll save you a fortune.” Sometimes that’s true. Sometimes it costs the owner money, adds a payroll headache they didn’t need, and shrinks a deduction they didn’t know they had.
Entity structure is one of the highest-leverage decisions a business owner makes, because it determines not just how much tax you pay but which taxes you pay, what deductions exist for you, how your retirement plan works, and what your eventual exit looks like. It’s also one of the most rule-of-thumb-infested corners of tax planning, and the rules of thumb have aged badly: the One Big Beautiful Bill Act changed enough of the underlying math in 2026 that structures chosen years ago deserve a fresh look.
We treat entity choice as a modeling question, not a threshold question. We built an in-house analyzer that computes the full picture, federal tax, payroll tax, the QBI deduction, state treatment, retirement capacity, and the double-tax math of a C corporation, side by side on a household’s actual numbers, because the right answer falls out of the interactions, not out of any single rule. This piece walks through what each structure actually does, what OBBBA changed, and the specific tradeoffs the modeling has to capture.
The default: sole proprietorship or LLC, and the self-employment tax problem
Most businesses start as a sole proprietorship or a single-member LLC, and for tax purposes those are the same thing: the business’s entire profit lands on the owner’s personal return, and all of it is subject to self-employment tax of 15.3% (the combined employee and employer shares of Social Security and Medicare) on earnings up to the Social Security wage base of $184,500 in 2026, with the 2.9% Medicare portion continuing above that, plus an additional Medicare surtax at higher incomes.
That’s the arithmetic that drives the entire S-corp conversation. A sole proprietor with $200,000 of profit pays self-employment tax on essentially all of it, whether the money was living expenses or reinvestment. There’s no distinction between “what I paid myself” and “what the business earned,” because legally there’s no difference. The LLC, for all its liability-protection virtues, changes nothing about this by default; an LLC is a legal wrapper, not a tax status, and until an election says otherwise it’s taxed exactly like the proprietorship it replaced.
To be clear about what the default structure gets right: it’s simple. No payroll system, no separate corporate return in most cases, no reasonable-compensation scrutiny, full flexibility on when and how you take money out. For a business with modest profit, simplicity frequently beats the alternatives on total cost once you account for what the alternatives require. The mistake isn’t starting here. The mistake is never re-examining it as profit grows.
The S election: a split, not a shield
An S corporation election (available to an LLC or corporation that meets the ownership requirements: broadly, no more than 100 shareholders, all U.S. persons, and a single class of stock, which matters for any owner planning to bring in outside investors) changes one central thing: it splits the business’s profit into two streams with different tax treatment.
Stream one: your salary. The owner must be paid a W-2 wage for the work they perform, and that wage carries the same payroll taxes any salary does.
Stream two: distributions. Profit above the salary flows to the owner as a distribution, and distributions are not subject to self-employment or payroll tax. That’s the entire engine of the strategy: every dollar of profit that legitimately sits in the distribution stream instead of the salary stream escapes the 15.3% (or 2.9%-plus) payroll layer.
The constraint holding the whole thing together is reasonable compensation. The IRS requires the salary to reflect what the owner’s work is actually worth, precisely because every dollar shifted from salary to distribution avoids payroll tax. An indefensibly low salary is the classic S-corp audit issue, and in our modeling the reasonable-compensation figure is a floor, never a variable: the optimization runs above it, not around it.
What the barbecue advice leaves out is everything the election costs and changes:
It costs administration. Payroll processing, quarterly filings, a separate S-corp return, and often higher accounting fees. Real dollars every year, which the payroll-tax savings must exceed before the election nets anything.
It changes your QBI deduction. Your salary is not qualified business income, so every dollar of owner salary shrinks the 20% QBI deduction’s base. Below the QBI income thresholds, that’s a pure cost of the election that partially offsets the payroll savings. Above the thresholds, the picture inverts: the salary becomes the W-2 wage base that the QBI limitation formula requires, and too little salary can cap the deduction harder than the salary itself shrinks it. We covered that paradox in depth in our QBI deduction piece; the short version is that the payroll-tax question and the QBI question have to be solved together, because they pull the optimal salary in different directions at different income levels.
It changes your retirement math. Retirement plan contributions key off W-2 compensation in an S corp. A very low salary caps what can flow into a solo 401(k) or fund a cash balance plan, which is why the salary that minimizes this year’s tax is often not the salary that maximizes long-term wealth. It also feeds your future Social Security benefit, which is small in any single year and meaningful over a career of low reported wages.
So when does the election make sense? Not at a magic revenue number. The honest answer is: when profit sits sustainably and comfortably above a defensible reasonable salary, by enough margin that the payroll-tax savings on the distribution stream clearly exceed the administrative cost and any QBI haircut, on a multi-year view. For one business that’s a lower number than the internet suggests; for another (an SSTB owner near the QBI phaseout, say) the election can be worth less than it looks. This is exactly why we model it rather than quote a threshold: our analyzer sweeps the salary range from the reasonable-compensation floor upward and computes the total federal, payroll, state, and QBI picture at each level, then projects it forward several years, because a structure that wins in year one can lose by year three as profit grows or the law shifts.
The C corporation: the seductive 21%, and the second bite
Every few years, usually after seeing the flat 21% corporate rate, an owner asks whether they should just be a C corporation. The rate is real, OBBBA left it untouched and permanent, and it’s lower than the top personal brackets. The catch is the second layer: a C corporation’s after-tax profit is taxed again when it reaches the owner as a dividend, at qualified-dividend rates plus, for higher earners, the 3.8% net investment income tax. Stack the layers and the combined rate on distributed profit typically exceeds what a pass-through owner pays once, especially since C-corporation income never qualifies for the 20% QBI deduction at all.
For a business that distributes its profits, the double tax usually settles the question against the C corporation. But there are three situations where the C structure genuinely competes, and OBBBA strengthened the third one considerably:
Heavy reinvestment. A business retaining most of its earnings to fund growth defers the second layer indefinitely; profit compounding inside the company faces only the 21%. (Early-stage companies running losses feel the double tax even less.)
International income. Cross-border earnings carry structural advantages inside a C corporation that pass-throughs largely can’t access.
A QSBS exit. Only C corporations can issue qualified small business stock under Section 1202, and OBBBA dramatically expanded the benefit for stock issued after July 4, 2025: a tiered gain exclusion (50% after a three-year hold, 75% after four years, 100% after five), an exclusion cap raised from $10 million to $15 million, indexed for inflation (or 10 times basis if greater), and a gross-asset eligibility threshold raised from $50 million to $75 million. For a founder building toward a sale, the possibility of excluding eight figures of gain from tax entirely can outweigh years of double-tax friction, and it’s pulled the C corporation back into serious consideration for more companies than the old rules did. The qualification requirements are genuinely technical, and we’ll cover QSBS in depth in its own piece; for entity selection, the takeaway is that your exit plan is now a first-order input to the structure decision, not an afterthought.
One more OBBBA note for pass-through owners in states with income taxes: the law preserved state pass-through entity tax (PTET) elections, the mechanism that lets S corps and partnerships deduct state taxes at the entity level around the personal SALT cap. For Texas-based owners there’s no state income tax to work around, but for the many business owners we serve with multistate operations or out-of-state residency, PTET availability remains a live input in the entity model.
The same profit is taxed through entirely different machinery depending on structure. Which machine wins depends on profit level, reinvestment plans, QBI position, and exit horizon, which is why the decision is modeled, not guessed.
Profit taxed: once, on your return
Payroll layer: 15.3% self-employment tax on essentially all profit up to the $184,500 wage base, 2.9%-plus above
QBI: full 20% deduction on qualifying profit
Wins on simplicity at modest profit
Profit taxed: once, split into salary + distributions
Payroll layer: only on the reasonable salary; distributions escape it
QBI: 20% on profit after salary; salary interacts with the wage limit
Wins when profit sits well above a defensible salary
Profit taxed: 21% at the entity, again as dividends when distributed
Payroll layer: on owner salary only
QBI: none
Wins on heavy reinvestment, international income, or a QSBS exit
Simplified comparison; 2026 figures. State treatment, health insurance, retirement plan design, and the additional Medicare surtax all shift the outcome, which is why the full analysis is run on actual numbers.
How we actually run the decision
Because the variables interact, we run entity selection as what we call a total entity optimization review: the same business, same profit, same household, computed three ways side by side.
The model captures the pieces that rules of thumb drop. Self-employment tax versus payroll tax at a swept range of salaries above the reasonable-compensation floor. The QBI deduction under each structure, at the household’s actual taxable income, with the wage-limit and SSTB mechanics applied. Retirement plan capacity at each salary level, with employee deferrals and employer contributions optimized jointly (they affect QBI differently). Health insurance treatment. State considerations. The C-corporation scenario with the full double-tax math, dividend rates, and NIIT. And then the whole thing projected forward several years with sensitivity analysis, because entity choice is a multi-year commitment being made with single-year information.
Two findings from running this repeatedly are worth sharing. First, the right structure changes over a business’s life more often than owners expect: the default LLC that was correct at $80,000 of profit, the S election that was correct at $250,000, and the C corporation that becomes interesting when a venture-scale exit enters the picture are all the same business at different stages. Structure should be revisited at every major profit shift, at every major law change (2026 qualifies), and whenever the exit horizon moves. Second, the most expensive versions of this decision we see aren’t the wrong initial choices; they’re the right initial choices left unexamined for a decade.
Bringing it together
Entity structure isn’t a tax trick, it’s the operating system your business’s taxes run on. The default LLC buys simplicity and full QBI at the cost of self-employment tax on every profit dollar. The S election splits profit into salary and distributions and saves payroll tax on the second stream, at the price of administration, a reasonable-compensation obligation, and a more complicated QBI calculation that has to be optimized rather than assumed. The C corporation trades the QBI deduction and accepts a second tax layer in exchange for a flat 21% on retained earnings and, since OBBBA, a dramatically more generous QSBS exit for qualifying companies.
None of those tradeoffs resolves at a barbecue. They resolve in a model, run on your actual numbers, re-run when the numbers or the law change. The owners who get this right aren’t the ones who picked the trendy structure; they’re the ones who treated the choice as a living decision and checked the math again when 2026 gave everyone a reason to.
Common Questions About Business Entity Structure
Does forming an LLC change how my business is taxed? By itself, no. An LLC is a legal structure, not a tax status. A single-member LLC is taxed exactly like a sole proprietorship (a multi-member LLC like a partnership) unless it elects otherwise: the full profit flows to your return and is generally subject to self-employment tax. The LLC’s value is liability protection and flexibility, including the flexibility to elect S-corporation taxation later without changing the legal entity.
How does an S corporation save on taxes? It splits profit into two streams. The owner takes a required reasonable W-2 salary, which carries normal payroll taxes, and the remaining profit flows out as distributions, which are not subject to self-employment or payroll tax. The savings equal the payroll tax avoided on the distribution stream, minus the election’s real costs: payroll administration, a separate return, and the effect of the salary on your QBI deduction.
What is reasonable compensation for an S corp owner? It’s the wage the IRS requires you to pay yourself for the work you actually perform, benchmarked to what the business would pay someone else to do it. Because every dollar shifted from salary to distributions avoids payroll tax, an unrealistically low salary is the classic S-corp audit target. In our analysis, reasonable compensation is a floor the optimization runs above, never a number to be minimized.
At what income does an S corp election make sense? There’s no universal threshold, despite the popular revenue rules of thumb. The election makes sense when profit sits sustainably above a defensible reasonable salary by enough margin that the payroll-tax savings clearly exceed the administrative costs and any reduction in the QBI deduction, evaluated over multiple years. The answer shifts with the owner’s total household income, QBI threshold position, SSTB status, retirement plan goals, and state situation, which is why we model it case by case rather than quoting a number.
Why would anyone choose a C corporation if profits are taxed twice? Three main reasons. A business reinvesting most of its earnings defers the second tax layer and compounds at the flat 21% corporate rate. Companies with international income have structural advantages inside a C corporation. And only C corporations can issue qualified small business stock: for stock issued after July 4, 2025, OBBBA allows a tiered exclusion of gain on a sale (50% at a three-year hold, 75% at four, 100% at five) up to $15 million (indexed for inflation) or 10 times basis, with the eligibility asset threshold raised to $75 million. For founders building toward a large exit, that exclusion can outweigh years of double-tax cost.
Should I revisit my entity structure because of OBBBA? Probably, if it’s been more than a couple of years or your profit has changed materially. OBBBA made the QBI deduction permanent and widened its phaseouts (helping pass-throughs), expanded QSBS dramatically (helping C corporations), preserved PTET workarounds (relevant in states with income taxes), and left the 21% corporate rate in place. Which way those changes cut depends entirely on your profit level, reinvestment plans, and exit horizon, which is exactly the kind of shift that justifies re-running the full comparison.
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