Taxation
Business & Startup Taxation
The legal form a business takes — sole proprietorship, partnership, or corporation — determines whether its profit is taxed once, or twice, before an owner ever sees it.
Definition
A pass-through entity(a sole proprietorship, a partnership, or most LLCs) isn't treated as its own separate taxpayer. Its profit "passes through" directly to the owners' personal tax returns and is taxed once, at each owner's individual tax rate — whether or not the profit was actually paid out to them in cash.
A C-corporation is treated as its own separate legal taxpayer, distinct from its owners (shareholders). The corporation pays corporate income tax on its own profit. If it then pays out some of that already-taxed profit to shareholders as a dividend, each shareholder pays personal income tax on that dividend too — so the same dollar of profit gets taxed twice: once at the corporate level, once at the shareholder level. This is called double taxation.
Why this exists
When a business earns profit, a tax system has to decide who counts as the taxpayer: the business itself, treated as its own legal "person," or only the individual owners. This isn't a minor bookkeeping detail — it's a fundamental design choice with real financial consequences, because it determines how many times the same dollar of profit gets taxed before an owner can actually spend it.
Pass-through treatment exists because, for a small business with one owner or a handful of partners, there's no meaningful difference between "the business" and "the person(s) who own it" — treating the business as a separate taxpayer on top of the owner would tax the exact same profit twice for no real reason. Corporate treatment exists because a large company with thousands of shareholders, ongoing outside investment, and shares that trade hands constantly genuinely needs to be treated as its own persistent legal entity, separate from whoever happens to own its stock at a given moment — and tax law follows that same separation.
Double taxation isn't an oversight — it's the direct consequence of treating the corporation as its own taxpayer. It also explains something from Cost of Capital: why interest paid to lenders is tax-deductible for a corporation, but dividends paid to shareholders aren't. Interest is deducted before the corporation's taxable profit is even calculated, and the lender then pays personal income tax on that interest — so that dollar is only taxed once in total. Dividends come out of profit that's already been taxed at the corporate level, and then get taxed again at the shareholder's level — a genuine second layer of tax that interest never goes through. That difference in tax treatment is a real, structural reason debt is cheaper than equity, not just an incidental rule.
Formula & mechanics
Pass-through: After-tax = Profit × (1 − Personal rate) C-corp, profit retained: After-tax (so far) = Profit × (1 − Corporate rate) C-corp, profit distributed: After-tax = Profit × (1 − Corporate rate) × (1 − Dividend rate)
"Retained" means the corporation keeps the profit instead of paying it out as a dividend — the second layer of tax is deferred, not eliminated, until the profit is eventually distributed or the shareholder sells stock whose value reflects that retained profit (taxed then as capital gains). That deferral has real value — per Retirement & Tax-Advantaged Accounts, delaying a tax bill lets the full pre-tax amount keep compounding in the meantime, the same underlying benefit as a Traditional-style retirement account.
Worked example
A business earns $100,000 of profit. Its owner is in a 32% personal tax bracket. The corporate tax rate is 21%, and the dividend tax rate is 15%.
Pass-through: $100,000 × (1 − 32%) = $68,000 after tax (effective rate: 32%) C-corp, profit retained (not yet distributed): $100,000 × (1 − 21%) = $79,000 after tax so far (effective rate: 21% — second layer deferred) C-corp, profit fully distributed as a dividend: $100,000 × (1 − 21%) × (1 − 15%) = $67,150 after tax (combined effective rate: 32.85%)
Notice how close the pass-through and fully-distributed C-corp outcomes end up here — $68,000 versus $67,150 — because today's corporate and dividend rates are both relatively low. Double taxation isn't automatically a disaster; how much it costs depends entirely on the specific rates involved, and it can be deferred substantially by retaining profit instead of distributing it right away.
Try it yourself
C-corp, fully distributed — combined effective rate
32.85%
Pass-through (after tax)
$68,000.00
C-corp, retained (after tax so far)
$79,000.00
C-corp, distributed (after tax)
$67,150.00
How the math works
Pass-through: $100,000.00 × (1 − 32%) = $68,000.00
C-corp, retained: $100,000.00 × (1 − 21%) = $79,000.00
(second layer of tax deferred until distributed)
C-corp, fully distributed: $100,000.00 × (1 − 21%) × (1 − 15%) = $67,150.00
(combined effective rate: 32.85%)The "C-corp, retained" figure isn't tax-free — it's the same profit taxed once so far, with the second layer deferred rather than eliminated. Whether double taxation ends up costing more than pass-through treatment depends entirely on how these three rates compare, and on how long distribution is delayed.
Common misconceptions
“A C-corporation always pays more total tax than a pass-through business.”
As the worked example shows, the gap depends entirely on the specific personal, corporate, and dividend tax rates involved, and retaining profit instead of distributing it defers the second layer of tax — sometimes for years, sometimes indefinitely.
“Self-employed people don't pay payroll tax since they don't have an employer.”
Per Payroll Taxes, a self-employed person owes 'self-employment tax' — both the employee's and the employer's share combined — because there's no separate employer to split the cost with. It doesn't disappear; it lands entirely on the individual.
“Choosing a business structure is purely a tax-minimization decision.”
Liability protection, the ability to raise outside investment, and the number and type of allowed owners often matter just as much as the tax outcome — venture-backed startups are almost always structured as C-corporations regardless of the tax trade-off, because investors typically require it.
Also in the Glossary: C-Corporation, Double Taxation, Pass-Through Entity