To calculate profit after tax, subtract cost of goods sold, operating expenses, interest, and your total tax liability from revenue; what remains is what the business actually keeps. Learning how to calculate profit after tax means working through the income statement in order — gross profit, operating income, pre-tax income, tax, and then the bottom line — and applying the right tax rate for your entity type. C corporations use a flat 21% federal rate. Pass-through owners (sole proprietors, partners, most LLCs, S corp shareholders) pay at individual rates that run from 10% to 37% for 2026, plus self-employment tax where it applies.
Numbers to Pull Before You Start
Open your income statement or profit and loss report and get four figures in front of you:
- Gross revenue — total sales before any deduction.
- Cost of goods sold (COGS) — direct costs of producing what you sell, such as raw materials and production labor.
- Operating expenses — rent, marketing, insurance, administrative salaries, and other overhead not tied to a specific product.
- Non-cash expenses — depreciation spreads the cost of tangible assets across their useful life, and amortization does the same for intangibles like patents. Both reduce taxable income even though no cash leaves the account.
You also need the tax rate that applies to your business. Corporations use the single federal rate. Pass-through owners need their personal marginal rate, which depends on filing status and total income. Pulling everything from your general ledger or accounting software first keeps you from backtracking mid-calculation.
The Five Steps From Revenue to Profit After Tax
The math peels away layers of cost until only the retained profit is left.
Step 1 — Gross profit. Revenue minus COGS. On $500,000 in revenue with $200,000 in COGS, gross profit is $300,000.
Step 2 — Operating income. Gross profit minus operating expenses, including depreciation and amortization. If operating expenses total $120,000, operating income is $180,000. This is how the core business performed before financing and taxes.
Step 3 — Pre-tax income. Adjust operating income for interest and any non-operating items (see next section). The result is the base your tax rate applies to.
Step 4 — Tax liability. Multiply pre-tax income by the applicable rate. A corporation with $180,000 in pre-tax income at 21% owes $37,800.
Step 5 — Profit after tax. Pre-tax income minus tax liability. In the same example, $180,000 minus $37,800 leaves $142,200.
Adjusting for Interest and Non-Operating Items
Operating income doesn’t include the cost of carrying debt or income earned outside normal operations. Before applying the tax rate, fold these in.
Interest expense on loans and credit lines gets subtracted from operating income. Interest earned on bank deposits, gains from selling an asset, and other non-operating income get added. The result is earnings before tax, the actual base for the tax calculation.
Corporations: The Flat 21% Rate
C corporations pay federal income tax as their own legal entity at a flat 21% of taxable income.1Office of the Law Revision Counsel. 26 US Code 11 – Tax Imposed The rate doesn’t move with income size, which keeps the calculation simple. A shortcut for a running estimate during the year: multiply pre-tax income by 0.79 to approximate what stays with the company after federal tax.
Pass-Through Entities: Where the Layers Stack
Sole proprietorships, partnerships, LLCs taxed as partnerships, and S corporations don’t pay federal income tax at the business level. Profit passes through to the owner’s personal return and is taxed at individual rates, which for 2026 run from 10% to 37% depending on total taxable income and filing status.2Internal Revenue Service. IRS Releases Tax Inflation Adjustments for Tax Year 2026 Because brackets are graduated, your effective rate on total income lands below the top bracket you reach.
Self-Employment Tax
Income tax isn’t the only tax cutting into pass-through profit. Sole proprietors and general partners also owe self-employment tax on business earnings at 15.3% — 12.4% for Social Security and 2.9% for Medicare.3Office of the Law Revision Counsel. 26 US Code 1401 – Rate of Tax The Social Security portion applies only to the first $184,500 of net self-employment income in 2026; the Medicare portion has no cap.4Social Security Administration. Contribution and Benefit Base An additional 0.9% Medicare tax applies once self-employment income exceeds $200,000 for single filers or $250,000 for married couples filing jointly.
Skipping self-employment tax is one of the most common mistakes owners make when running this calculation. On $150,000 of net business income, self-employment tax alone runs about $21,200 before income tax enters the picture. Half of the self-employment tax is deductible when calculating adjusted gross income, which lowers the income tax piece.
The Qualified Business Income Deduction
Pass-through owners may qualify for the Section 199A deduction, which allows a deduction of up to 20% of qualified business income before income tax is calculated.5Office of the Law Revision Counsel. 26 US Code 199A – Qualified Business Income On $150,000 of qualified income, that’s a potential $30,000 deduction, cutting the taxable amount to $120,000. It reduces income tax only, not self-employment tax.
Limits apply. Service-based businesses like law firms, medical practices, and consulting companies start losing access once the owner’s taxable income crosses certain thresholds. The deduction also can’t exceed the greater of 50% of W-2 wages paid by the business, or 25% of W-2 wages plus 2.5% of the cost basis of qualifying business property.5Office of the Law Revision Counsel. 26 US Code 199A – Qualified Business Income Sole proprietors with no employees and few capital assets often see a smaller deduction than they expect.
Adding State and Local Tax
The rates above cover federal tax only. Most states impose their own corporate or personal income tax, and that additional layer changes the profit-after-tax number meaningfully. State corporate income tax rates run from around 2% to nearly 12%. A handful of states impose no corporate income tax, though some substitute franchise taxes or gross receipts taxes.
For pass-through owners, state personal income tax applies on top of federal, and some cities add a local income tax. Add the combined state and local rate to the federal rate to get a realistic picture. An owner in a state with a 6% income tax who also falls in the 24% federal bracket faces a combined marginal rate closer to 30% before self-employment tax.
Using a Prior Year’s Loss
If the business lost money in a prior year, that loss doesn’t vanish. A net operating loss (NOL) carried forward from an earlier year offsets taxable income in a profitable year, reducing the tax piece of your calculation. Under current federal rules, the deduction for carried-forward losses is capped at 80% of taxable income in any given year.6Office of the Law Revision Counsel. 26 US Code 172 – Net Operating Loss Deduction Unused NOL rolls forward with no expiration date.
The 80% cap means old losses can’t zero out a whole tax bill. With $200,000 in taxable income this year and a $250,000 NOL carryforward, you can deduct $160,000 (80% of $200,000), leaving $40,000 taxable. The remaining $90,000 of NOL carries forward again.
A Worked Pass-Through Example
The corporate version is one multiplication, so a sole proprietor makes the better example because the layers stack up.
Suppose the business generates $400,000 in revenue, with $150,000 in COGS and $100,000 in operating expenses (depreciation included). Operating income is $150,000. After $5,000 in interest expense on a business loan, pre-tax income is $145,000.
- Self-employment tax: roughly $20,500 (15.3% of 92.35% of net earnings). About $10,250 of that is deductible against income tax.
- QBI deduction: up to 20% of qualified business income, potentially $29,000 if you qualify in full.
- Taxable income: $145,000 minus $10,250 (half of SE tax) minus $29,000 (QBI) is approximately $105,750, before the standard deduction.
- Federal income tax: calculated across the graduated brackets, roughly $17,000 for a single filer after the standard deduction.
- State income tax: varies; at 5%, around $5,300.
- Total tax burden: approximately $42,800 ($20,500 SE plus $17,000 federal plus $5,300 state).
- Profit after tax: $145,000 minus $42,800 is roughly $102,200.
That’s an effective total tax rate of about 29.5%, higher than the 21% a C corporation would pay on the same income. The comparison isn’t apples-to-apples, since corporate profits get taxed again when distributed as dividends. The takeaway for the calculation itself: a pass-through profit-after-tax number that skips any of these layers will come out too high.
Turning the Number Into Quarterly Payments
Calculating profit after tax at year end tells you what the business kept, but the IRS wants the tax paid across the year, not all at once. Individuals who expect to owe $1,000 or more at filing generally must make quarterly estimated payments. Corporations face the same requirement when expected liability exceeds $500.7Internal Revenue Service. Estimated Taxes
Missing a payment or underestimating triggers a penalty. You can generally avoid it by paying at least 90% of the current year’s tax or 100% of the prior year’s, whichever is smaller.7Internal Revenue Service. Estimated Taxes Running your profit-after-tax calculation at the close of each quarter, rather than once at year end, gives you the numbers to size those payments and keeps April from being a surprise.