Corporate Tax Calculator
Model both layers of corporate tax — the 21% the company pays, and the second bite the shareholder takes when the profit finally comes out.
Corporate Tax Calculator
Results recalculate instantly on every keystroke. Nothing you type is transmitted.
What this result does not account for
- Assumes distributions are qualified dividends; non-qualified distributions are taxed at ordinary rates.
- Accumulated earnings tax, personal holding company tax and the IRC 1202 small business stock exclusion are not modelled.
- Owner salary must be entered as a reduction in profit before it reaches this tool.
In short: A C-corporation earning $400,000 pays $84,000 at 21%, but distributing the remaining $316,000 adds $40,346.25 of dividend tax and $4,408.00 of NIIT. The true effective rate is 32.19%, not 21% — the second layer adds 11.19 points. Retaining the profit defers $44,754.25 of that.
Formula
Qualified dividends stack on top of ordinary income and are taxed in the 0%, 15% and 20% bands. NIIT adds 3.8% on the lesser of net investment income or modified AGI above $200,000 for a single filer.
Worked Example
- Tax the company. $400,000 of profit at 21% is $84,000, leaving $316,000 inside the corporation.
- Distribute what is left. Paying out all $316,000 as a qualified dividend triggers a second, entirely separate tax at the shareholder level.
- Tax the shareholder. $316,000 stacked above zero ordinary income falls mostly in the 15% band, producing $40,346.25.
- Add the investment surtax. MAGI of $316,000 exceeds $200,000, so NIIT adds 3.8% on the excess — $4,408.00.
- Read the true rate. $128,754.25 of total tax on $400,000 is 32.19%, not the 21% headline. The second layer costs 11.19 percentage points.
This is why the C-corporation's 21% rate is misleading for an owner-operated business. The 21% is only the cost of leaving money inside the company. Every dollar you actually take out is taxed a second time, and no amount of corporate planning changes that arithmetic.
Strengths & Limits Of This Model
Where this engine is strong
- Models both layers of tax, which is the whole point and is what a 21% headline hides.
- Shows the deferral value of retaining profit separately from any permanent saving.
- Treats state corporate tax as federally deductible rather than simply adding the rates.
Where it stops
- Does not compare against pass-through structures — use the Business Tax engine for that.
- Ignores payroll tax on owner salary, which is modelled elsewhere.
- Cannot capture multi-state apportionment, which drives real corporate rates.
Practical Use Cases
Deciding between a C-corp and a pass-through
The 21% rate only wins if profit stays in the business. Compare the alternatives with the Business Tax Calculator.
Planning a distribution policy
Retaining profit defers $44,754.25 here. That is a deferral, not a saving — the tax lands whenever the money finally leaves.
Choosing between salary and dividend
Salary is deductible to the company and taxed once; a dividend is not deductible and taxed twice. Reasonable salary almost always beats dividend for an owner-operator.
Modelling a company sale
Retained earnings inside a C-corp are eventually taxed on distribution or liquidation — factor that into any valuation with the Net Worth Calculator.
Methodology & Editorial Standards
The federal corporate rate has been a flat 21% since the Tax Cuts and Jobs Act and was not changed by the One Big Beautiful Bill Act. State corporate tax is modelled as a flat rate and treated as deductible against federal taxable income, which is why the two rates do not simply add. Distributions are assumed to be qualified dividends taxed in the 0/15/20% bands, stacked above the shareholder's other ordinary income. NIIT applies at 3.8% on the lesser of net investment income or MAGI above $200,000 for a single filer. The engine does not model accumulated earnings tax, personal holding company tax, the corporate AMT on very large corporations, or the qualified small business stock exclusion under IRC 1202, any of which can materially change the picture. Salary paid to owner-employees should be entered as a reduction in profit before it reaches this tool. The engine implements the standard published formula for this calculation. Inputs are validated for domain and sign before evaluation, and any undefined case returns an em-dash rather than a spurious value.
Computation runs in IEEE-754 double precision at full internal precision; rounding to two decimal places occurs strictly at the display layer, so no cumulative drift enters the result. All monetary outputs use accounting presentation — grouped thousands, two decimals, negatives in parentheses — so figures can be transcribed directly into a model or working paper. Division-by-zero and out-of-domain inputs return an em-dash rather than a misleading number.
This engine was reconciled against an independent reference implementation and hand-verified for the worked example above before release. Our full five-stage review process is published on the About Us page.
Disclaimer. This calculator is provided for informational and modelling purposes only and does not constitute financial, tax, legal, medical, or engineering advice. Verify all figures with a qualified professional before acting on them.
Corporate Tax Calculator — 20 Expert FAQs
20 analyst-written answers to the questions practitioners actually ask — optimised for voice and answer-engine retrieval.
What is the corporate tax rate?
A flat 21% federally since 2018, unchanged by the One Big Beautiful Bill Act. Most states add their own, and state corporate tax is deductible against federal taxable income.
What is double taxation?
Corporate profit is taxed once at the company and again when distributed to shareholders. Here $400,000 attracts $84,000 of corporate tax and a further $44,754.25 at the shareholder.
Is a C-corp really taxed at only 21%?
Only if the money never comes out. Distribute it and the true effective rate here is 32.19% — the second layer adds 11.19 percentage points.
How can I avoid double taxation?
Pay reasonable salary, which is deductible to the company and taxed once; make employer retirement contributions; or elect S-corporation status so profit passes through untaxed at entity level.
Should I retain profit inside the company?
Retaining defers the second layer — $44,754.25 here — but does not avoid it. The tax lands whenever the money is finally distributed or the company is liquidated.
Are dividends taxed at a lower rate?
Qualified dividends are taxed at 0%, 15% or 20% rather than ordinary rates, which softens the second layer considerably but does not eliminate it.
What is NIIT and does it apply to dividends?
The Net Investment Income Tax adds 3.8% on the lesser of net investment income or MAGI above $200,000 for a single filer. Dividends are net investment income, so yes.
Is an LLC taxed as a corporation?
Not by default. An LLC is a pass-through unless it elects corporate treatment, in which case it is taxed exactly like a C-corp including the second layer.
When does a C-corp actually make sense?
When profit is genuinely reinvested rather than distributed, when you need many classes of stock or institutional investors, or when the qualified small business stock exclusion is in reach.
Do I still pay payroll tax in a C-corp?
Yes, on any salary you take. That salary is deductible to the company, which is precisely why it is more efficient than a dividend for an owner-operator.
Can a C-corp deduct my salary?
Yes, provided it is reasonable for the work performed. Excessive compensation can be recharacterised as a disguised dividend and lose the deduction.
What is accumulated earnings tax?
A 20% penalty on profits retained beyond the reasonable needs of the business, designed to stop companies hoarding earnings purely to defer shareholder tax.
Do state corporate taxes add to the 21%?
Not directly. State tax is deductible federally, so a 6% state rate adds roughly 4.7 points after the federal deduction rather than a full 6.
How does this compare to an S-corporation?
An S-corp has no entity-level tax at all — profit flows to your personal return once. That single-layer treatment is usually decisive for a small owner-managed business.
Is the 21% rate permanent?
It has no scheduled expiry, unlike the individual provisions which needed the One Big Beautiful Bill Act to be made permanent. It can of course still be changed by future legislation.
Is this corporate tax calculator free to use?
Yes. It is free, requires no account, and has no usage limits. ApexConverter is funded by contextual advertising, never by selling user data.
Is my data sent to a server?
No. The engine runs as Vanilla JavaScript inside your browser under our Zero-Server Client-Side Execution model. Your figures are computed locally and are never transmitted, logged, or stored.
How accurate is this calculator?
It applies the standard closed-form formula in IEEE-754 double precision, rounding only at the display layer. The engine is reconciled against an independent reference implementation before release.
Does it work on mobile?
Yes. The interface is mobile-first with numeric keypad hints and is tested down to a 320-pixel viewport with no horizontal scrolling.
Can I use it offline?
Largely, yes. Because computation is client-side, the page continues to calculate without a network connection once it has loaded.