This article summarizes general US corporate tax rules for informational purposes.

It is not legal or tax advice — entity choice has long-term consequences for financing, equity, and exit strategy, and should be reviewed with a CPA or business attorney before you file anything with the IRS.

Key Takeaways

A C-Corp pays a flat 21% federal corporate tax on its profits, and then shareholders pay tax again on any dividends at 0%, 15%, or 20% — the "double taxation" that gives S-Corps their reputation as the small-owner-friendly choice.
An S-Corp pays no federal corporate tax at all; profit passes straight through to the owner's personal return and is taxed once, at individual rates of 10% to 37%.
On $100,000 of profit fully distributed to a single owner, the gap between the two structures can run in the range of $8,000 to $9,000 in extra tax under the C-Corp path — real money that compounds every year profit gets paid out.
Both structures give identical liability protection; the choice between them is a tax and financing decision, not a legal-protection one.
C-Corps still win for a specific kind of business: one raising venture capital, planning to reinvest most profit rather than distribute it, or aiming for a future exit that could qualify for the Section 1202 Qualified Small Business Stock exclusion — a benefit S-Corps and LLCs can't access.

The corporate-tax math, worked through

Every corporation, when it's first formed at the state level, defaults to C-Corp status — S-Corp treatment is an election you make afterward by filing IRS Form 2553, not a separate legal entity type. The distinction matters entirely at the point profit gets taxed.

A C-Corp pays the flat 21% federal rate on its net income, a rate that's held steady since the 2017 tax reform and remains unchanged for 2026. If the company keeps that after-tax profit inside the business — reinvesting it, building cash reserves, funding growth — the story stops there for the year. The second tax only shows up when the corporation actually pays a dividend to its shareholders, taxed again at qualified dividend rates of 0%, 15%, or 20%, plus a possible 3.8% net investment income tax for higher earners.

Run the numbers on $100,000 of profit paid out in full: the corporation pays $21,000 in corporate tax, leaving $79,000. Distributed as a dividend and taxed at a 15% rate, that adds roughly $11,850 more, for a combined tax bill near $32,850 — against a comparable S-Corp scenario where that same $100,000, taxed once at a roughly 24% personal rate, produces about $24,000 in tax. The gap, in this example, is close to $8,850, and it repeats every year the business distributes profit rather than retaining it.

Why anyone would still choose the C-Corp

Given that math, the C-Corp looks like an obvious loser for a small, profit-distributing business — and for that specific case, it usually is. But the calculation flips for businesses built around a very different goal: retaining and reinvesting profit rather than distributing it, and eventually selling the company or its shares.

C-Corps have no cap on the number of shareholders and can issue multiple classes of stock, which is exactly the structure most venture capital investment requires — an S-Corp is legally capped at 100 shareholders and one class of stock, ruling it out for most VC-backed companies from the start. C-Corps are also the only structure eligible for the Section 1202 Qualified Small Business Stock exclusion, which can shelter a meaningful portion of gain — up to $15 million in certain cases — from federal tax on a future sale, an advantage large enough to justify absorbing double taxation during the operating years for a company genuinely aiming at that kind of exit.

What the S-Corp asks of you in return

The S-Corp's single layer of tax isn't free of its own requirements. Owners who materially work in the business must pay themselves a "reasonable salary" subject to payroll tax, with only the remaining profit distributed free of self-employment tax — the same mechanism that makes an LLC's S-Corp election valuable, and the same one that requires running actual payroll, filing a separate informational return (Form 1120S), and keeping tighter books than a simple pass-through entity demands.

On top of the reasonable-salary requirement, S-Corp owners can still generally claim the 20% Qualified Business Income deduction on their pass-through share of profit, a benefit that's been made a permanent part of the tax code and stacks on top of the single-layer tax treatment to widen the gap versus a C-Corp even further for a typical profitable small business.

What this means if you're choosing between the two

If your business's whole point is to generate income you'll live on, the S-Corp's single layer of tax is very hard for a C-Corp to beat. Unless you have a specific reason to retain earnings inside the company for years at a time, distributing profit through a C-Corp means paying that second layer of tax repeatedly.
If you're planning to raise venture capital or take on investors who require preferred stock, the C-Corp isn't really optional. Most institutional investors won't invest in an S-Corp structure at all, since the shareholder cap and single-stock-class rule make their preferred terms impossible to implement.
If a future acquisition or IPO is realistically on the table, look into whether your stock could qualify for the Section 1202 exclusion before ruling out the C-Corp on tax grounds alone. The exclusion can outweigh years of double taxation if the eventual gain is large enough.
Either way, remember the liability protection is identical. Don't let entity comparisons about tax treatment imply one structure protects your personal assets better than the other — they don't; the tax election and the liability shield are two separate questions entirely.

Frequently Asked Questions

Can an LLC elect S-Corp tax treatment, or does S-Corp only apply to actual corporations? An LLC can elect to be taxed as an S-Corp by filing Form 2553 without changing its underlying legal structure — it stays an LLC for state-law purposes while being taxed like an S-Corp for federal purposes. This is a common path for growing single-member LLCs once profit reaches a level where the payroll-tax savings outweigh the added administrative cost.

Is the 21% C-Corp tax rate likely to change again soon? The flat 21% rate was made permanent by the 2017 tax reform and has not been altered by more recent legislation as of 2026, though corporate tax rates are set by Congress and can change with future legislation — this is worth revisiting periodically rather than assuming permanence indefinitely.

Does choosing a C-Corp mean I'll definitely face double taxation? Only on profit that's actually distributed as a dividend. A C-Corp that reinvests all of its profit back into the business — equipment, hiring, growth — pays the 21% corporate rate but doesn't trigger the second layer of tax until and unless it later distributes that money to shareholders.

How do I actually elect S-Corp status once I've decided it's right for me? File IRS Form 2553 within two months and fifteen days of the start of your tax year for the election to apply to that year — for most calendar-year businesses, that's a mid-March deadline. Missing that window generally pushes the election to the following tax year, so timing matters if you want the savings sooner rather than later.

Sources & References

Formations Corp, "S-Corp vs. C-Corp: Which Saves Self-Employed Owners More in 2026?"
SDO CPA, "S-Corp vs C-Corp Taxes: Which Saves More? (2026)"
1800Accountant, "S Corp vs. C Corp: Key Differences and How to Choose Best Structure"
StartupOwl, "C Corp vs S Corp: Key Differences and Tax Savings (2026)"
Otterz, "LLC vs S-Corp vs C-Corp: 2026 Tax Comparison Guide"
Coto Waddington, "Difference Between S Corp and C Corp: A Founder's 2026 Guide"

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