The confusion is structural. State law gives you entity types — sole proprietorship, partnership, LLC, corporation. Federal tax law gives you classifications — disregarded entity, partnership, S corporation, C corporation. These two systems overlap but are not the same, and conflating them produces most of the bad advice circulating online.
A single-member LLC is, by default, a disregarded entity: taxed exactly like a sole proprietorship. Forming it changes your liability exposure and nothing else about your tax bill. That surprises people who paid a formation service expecting savings.
What each structure actually does
| Sole prop | LLC (default) | LLC + S-corp | C-corp | |
|---|---|---|---|---|
| Liability shield | None | Yes | Yes | Yes |
| Self-employment tax | All profit | All profit | Salary only | Salary only |
| Entity-level tax | No | No | No | 21% federal |
| Payroll required | No | No | Yes | Yes |
| QBI deduction eligible | Yes | Yes | Yes | No |
| Outside investors | No | Awkward | Limited (100 holders, one class) | Designed for it |
| Annual admin burden | Minimal | Low | Moderate | High |
The mental modelForm the LLC for liability. Elect S-corp treatment when profit is high enough that the self-employment saving exceeds the payroll cost. Reach for a C-corp only when the cap table requires it.
Where the S-corp saving comes from
Self-employment tax is 15.3% on net earnings — 12.4% Social Security up to the annual wage base, plus 2.9% Medicare with no ceiling. A default LLC owner pays it on all profit. An S-corp owner pays it only on W-2 salary; distributions above that escape the levy.
The saving is therefore profit minus salary, multiplied by roughly 15.3%, minus the cost of running payroll and filing an 1120-S. That last term is what makes the election a genuine calculation rather than a default.
Reasonable compensation: the whole audit risk
The election works only if your salary is defensible. Pay yourself $20,000 on $300,000 of profit and you have not been clever — you have created an examination file with reclassification, back payroll tax, interest and penalties waiting at the end of it.
- Benchmark the role, not the ownerWhat would you pay an employee to do your job? Use BLS wage data or industry salary surveys for your region.
- Split the functionsIf you do sales, delivery and admin, weight market rates by hours spent in each. This produces a documented, defensible figure.
- Apply a profit split testSalary somewhere between 40% and 60% of profit is a widely used comfort zone for service businesses. Capital-intensive businesses can justify less.
- Document it once a yearA one-page memo with your sources and reasoning is the cheapest audit insurance available.
- Revisit as profit growsA salary set at $60k when profit was $120k is hard to defend when profit reaches $400k.
The reclassification cascadeIf distributions are reclassified as wages, you owe back payroll tax on the reclassified amount plus penalties — and because payroll filings were wrong, the exposure spans every quarter of every open year.
The QBI interaction people miss
The qualified business income deduction can shelter up to 20% of pass-through income, but it phases out for specified service businesses above income thresholds, and above those thresholds the deduction becomes limited by W-2 wages paid. That creates an awkward tension: lowering your salary raises the SE-tax saving but can reduce the wage base that supports your QBI deduction.
Below the thresholds the interaction is usually irrelevant. Above them, it is genuinely a two-variable optimisation and one of the few situations where paying for modelling is clearly worth it.
When a C-corp is the right answer
Choose C-corp when
- Institutional investors require it — most funds cannot hold pass-through interests
- You are planning an equity compensation programme with option pools
- Qualified small business stock treatment could exclude significant gain at exit
- You intend to retain earnings inside the business for years rather than distribute
- You need more than one class of stock or foreign shareholders
Avoid C-corp when
- You take most profit out annually — double taxation applies to every dollar distributed
- You are the only owner with no funding plans
- Your business generates losses you would rather use personally
- Administrative overhead would exceed the tax benefit
- You would forfeit a meaningful QBI deduction to get there
Limits, errors and borders of the standard advice
Critical reviewEntity advice is dominated by formation services paid per registration and by content optimised for people searching at the most anxious moment of starting a business. Both favour acting quickly over acting correctly.
"Form an LLC immediately to protect your personal assets."
The claimA limited liability entity shields personal assets from business claims.
Where it breaksThe protection is real and narrower than advertised. It does not cover your own negligence or professional malpractice, personally guaranteed debts — which is most small-business lending — unpaid payroll taxes, or fraud. It can also be disregarded where the entity is not maintained as genuinely separate: mixed bank accounts, no records, personal expenses paid from business funds. Single-member entities receive less protection in some jurisdictions than owners assume. And for a pre-revenue business with no employees and no premises, the liability being shielded is often close to zero, while adequate insurance would address more of the real exposure than the entity does.
The borderFormation matters once there are employees, premises, physical risk, contracts of consequence or meaningful assets to protect. Before that, appropriate insurance frequently does more. And whatever you form, maintain the separation — an entity treated casually provides much less protection than its owner believes.
"Elect S-corp status to save on self-employment tax."
The claimSplitting income between salary and distributions reduces employment taxes substantially.
Where it breaksThe saving is real above a certain profit level and it is quoted without its costs. Payroll administration, additional filings and higher accounting fees are recurring, and below a threshold of profit they consume the entire benefit — the calculators promoting this rarely subtract them honestly. The salary must also be reasonable for the work performed, which is a genuine constraint and a known examination focus; the aggressive low-salary versions circulating online are the ones that attract attention. Lower reported wages can additionally reduce future social-insurance entitlements and retirement contribution capacity.
The borderWorth modelling once profit is comfortably above the level where the saving clearly exceeds the added compliance cost, the income is stable, and you will actually run payroll properly. Not worth it for a small or volatile profit, and not worth it if the plan depends on an indefensibly low salary.
"Register in a business-friendly state — the laws are better."
The claimCertain jurisdictions offer superior corporate law and lower taxes.
Where it breaksRegistering elsewhere generally does not remove your obligations where you actually operate — you typically must register as a foreign entity there anyway, paying both sets of fees and filing both sets of returns, and you are taxed on the basis of where the activity occurs. So the common outcome is double administration for no tax benefit. The corporate-law advantages are real for companies raising institutional capital with sophisticated governance needs, and largely irrelevant to a small operating business. Registered-agent and compliance services promoting this benefit from the extra registration.
The borderChoose the jurisdiction where you operate unless you are raising venture capital, planning a structure investors will expect, or have a specific legal reason. The costs of a mismatched registration are certain; the benefits usually are not.
"The entity type is a big decision — get it right from the start."
The claimEntity choice is foundational and difficult to change, so it must be resolved first.
Where it breaksIt overstates the irreversibility, and the anxiety it creates is useful to people selling formation packages. Tax classification can often be elected or changed later, and entities can be converted — the friction is real but far from prohibitive. Meanwhile the decision is presented as more consequential than the things that actually determine whether the business survives: whether anyone pays for the product, pricing, cash flow and customer acquisition. Founders routinely spend weeks on structure before validating demand.
The borderSome decisions genuinely are hard to unwind — issuing equity to multiple parties, admitting foreign owners, or structures with immediate tax consequences on conversion. Get advice for those. Otherwise start simple, validate the business, and revisit structure when profit or complexity justifies it.
The entity types discussed exist in one country's law, and readers elsewhere face different forms with different consequences — the comparison may not translate at all. We give no thresholds or rates, so the break-even calculations we recommend need current local figures and, realistically, an accountant. And our advice to defer structural decisions is right on average and wrong for the specific founder who takes on a co-owner or a large contract early: for them, the informal start creates exactly the problem we told them not to worry about.
Frequently asked questions
Can I elect S-corp status mid-year?
An election filed on Form 2553 is generally effective for the current tax year if submitted within two months and fifteen days of the start of that year. Later filings usually take effect the following year, though relief for a late election exists where there was reasonable cause.
Does an S-corp reduce my income tax?
No. Profit still flows through to your personal return either way. The election addresses self-employment tax specifically. Anyone promising income tax savings from the election alone is describing something else — or nothing.
Do I need a separate bank account and bookkeeping?
Yes, and it matters more than owners expect. Commingling funds is the classic argument for piercing the liability shield, which defeats the reason you formed the entity. Separate accounts, a real payroll register and clean books are the price of the protection.
What if my profit fluctuates year to year?
The election is not annual — once made it persists until revoked, and revoking has a five-year re-election waiting period. If profit is volatile around the breakeven point, favour stability: elect when the multi-year average clearly clears the threshold, not on a single strong year.
The bottom line
Form an LLC for liability protection regardless. Run the S-corp numbers once profit clears roughly $45,000, and elect when the saving comfortably exceeds payroll and filing costs across a normal year — not a peak one. Then set a documented, defensible salary and revisit it annually. Reserve the C-corp for genuine fundraising or QSBS strategy. Once the structure is right, turn to the deduction discipline that lowers the taxable profit the structure sits on.
Revision log. Jul 2026: added S-corp election model and expanded reasonable-compensation methodology. Reviewed quarterly. This is educational information, not tax advice.