A profit and loss statement is built by subtracting your business expenses from your business revenue over a set period to arrive at net income. To do a profit and loss statement step by step, you choose an accounting method, gather your income and expense records, then work through five calculations: total revenue, cost of goods sold, gross profit, operating expenses, and net income. That final figure is what flows onto Schedule C and drives most of the tax math you’ll face as a business owner.
Pick an Accounting Method First
Before you add up a single number, decide how your business recognizes income and expenses. The IRS holds you to whichever method you choose unless you get permission to switch, so this choice shapes every P&L that follows.
The cash method counts income when payment actually arrives and expenses when money leaves your account. Most sole proprietors and small businesses use it because it matches what they see in the bank. Under Internal Revenue Code Section 448, a business qualifies for the cash method as long as its average annual gross receipts over the prior three tax years don’t exceed $32 million (the inflation-adjusted threshold for 2026).1Internal Revenue Service. Rev. Proc. 2025-32
The accrual method records revenue when you earn it and expenses when you incur them, regardless of when cash changes hands. If you invoice a client in November and get paid in January, accrual counts that revenue in November. Larger businesses and those that don’t meet the gross receipts test must use this method. Accrual gives a more complete picture once billing and payment timing starts to distort monthly results.
Gather Your Records
Accurate records are the raw material of a useful P&L. On the income side, pull together invoices, sales receipts, payment processor statements, and 1099 forms. You want a full picture of gross revenue before any expenses.
On the expense side, gather bank and credit card statements, supplier invoices, payroll records, rent and lease agreements, and receipts for anything you plan to deduct. Sort your costs into two buckets: direct costs tied to producing your product or service (cost of goods sold), and operating expenses like rent, utilities, insurance, and office supplies. Schedule C organizes deductions into specific line items — advertising, car expenses, insurance, legal and professional fees, office supplies, and so on — so sorting your records into those categories now saves work later.2Internal Revenue Service. Instructions for Schedule C (Form 1040) (2025)
If your business sells physical products, you also need beginning and ending inventory figures along with a record of purchases or production during the period. Businesses that meet the $32 million gross receipts test can treat inventory as non-incidental materials and supplies, which simplifies the process considerably.3eCFR. 26 CFR 1.471-1 – Need for Inventories
Work Through the Five-Step Calculation
The math follows a straightforward sequence. Each step peels away a layer of costs to move you closer to the bottom line.
Step 1: Total Revenue
Add every dollar your business earned during the reporting period: sales of products and services, commissions, fees, and any other business income. Subtract refunds and returns from that gross figure to arrive at net revenue.
Step 2: Cost of Goods Sold
If you sell physical products, subtract the direct costs of producing or purchasing them. Cost of goods sold typically includes raw materials, manufacturing labor, shipping to your warehouse, and packaging. The formula is beginning inventory plus purchases during the period, minus ending inventory. Service businesses without inventory skip this step.
Step 3: Gross Profit
Revenue minus cost of goods sold equals gross profit. This is how much money is left to cover everything else: rent, salaries, marketing, and your own compensation. A shrinking gross profit margin over time usually means production costs are rising faster than your prices.
Step 4: Operating Expenses
Subtract all the expenses required to run the business that aren’t directly tied to producing your product. Typical categories include rent, utilities, insurance, office supplies, advertising, professional fees, and payroll. Schedule C lines 8 through 27 walk through these categories systematically.4Internal Revenue Service. Instructions for Schedule C (Form 1040) (2025) – Section: Part II. Expenses A few of these categories have rules worth knowing before you finalize the totals, covered in the next section.
Step 5: Net Income
Gross profit minus total operating expenses equals your net income, or a net loss if expenses exceeded revenue. This is the figure that flows to your personal tax return on Schedule C, Line 31, and it’s the starting point for calculating what you owe.5Internal Revenue Service. About Schedule C (Form 1040), Profit or Loss from Business (Sole Proprietorship)
Rules That Shape the Expense Side
A handful of common deductions come with limits or choices that affect how much lands on your operating expense line. Get these right before you finalize step 4.
Home Office
If you use part of your home regularly and exclusively for business, you can deduct a portion of your housing costs. The simplified method allows $5 per square foot of dedicated office space, up to 300 square feet ($1,500).6Internal Revenue Service. Simplified Option for Home Office Deduction The regular method uses Form 8829 and applies the business-use percentage of your home to actual expenses like mortgage interest, insurance, utilities, and repairs. It’s more work but often produces a larger deduction.
Vehicle Expenses
You can deduct either actual vehicle expenses (gas, insurance, repairs, depreciation) or use the IRS standard mileage rate, but not both in the same year. Either way, keep a log of business miles. Personal commuting doesn’t count.7Internal Revenue Service. Instructions for Schedule C (Form 1040) (2025) – Section: Line 9
Business Meals
Meals with a clear business purpose are deductible at 50% of the cost.8Internal Revenue Service. Business Travel Expenses Entertainment expenses like sporting events and concerts are not deductible. Keep receipts noting attendees and the business purpose, because the IRS scrutinizes meal deductions closely.
Depreciation and Section 179
When you buy equipment, furniture, or other business assets with a useful life beyond one year, you generally spread the cost over that useful life through depreciation rather than deducting it all at once. Two provisions let you accelerate the write-off. Section 179 allows you to deduct up to $2,560,000 of qualifying equipment costs in the year you place the property in service, with the deduction phasing out once total qualifying purchases exceed $4,090,000. Bonus depreciation, reinstated at 100% for qualifying property placed in service after January 19, 2025, lets you write off the full cost of eligible assets in year one without the Section 179 spending cap.9Internal Revenue Service. One, Big, Beautiful Bill Provisions In a year of large purchases, these provisions can significantly reduce net income on paper.
What Your Net Income Triggers on the Tax Side
The net income line isn’t just a performance metric. It drives several tax obligations that catch new business owners off guard.
Self-Employment Tax
If your net earnings from self-employment are $400 or more, you owe self-employment tax on top of income tax. The combined rate is 15.3%: 12.4% for Social Security and 2.9% for Medicare, covering both the employer and employee shares.10Internal Revenue Service. Self-Employment Tax (Social Security and Medicare Taxes) The Social Security portion applies only to the first $184,500 of combined wages and self-employment earnings in 2026.11Social Security Administration. Contribution and Benefit Base The Medicare portion has no cap, and an additional 0.9% Medicare surtax applies to self-employment income above $200,000 for single filers ($250,000 for married filing jointly).
Two details soften the hit: you calculate SE tax on 92.35% of your net self-employment earnings, and you can deduct half of what you pay when figuring adjusted gross income.
Quarterly Estimated Payments
No employer is withholding tax from your pay, so the IRS expects quarterly estimated payments. You generally must pay if you expect to owe at least $1,000 in tax for the year after withholding and refundable credits.12Internal Revenue Service. Estimated Tax The 2026 due dates are April 15, June 15, September 15, and January 15, 2027. You can skip the January payment if you file your 2026 return and pay the balance by February 1, 2027.13Internal Revenue Service. 2026 Form 1040-ES Missing a deadline triggers a penalty even if you’re ultimately owed a refund.
Qualified Business Income Deduction
Sole proprietors, partners, and S corporation shareholders can deduct up to 20% of qualified business income under Section 199A.14Office of the Law Revision Counsel. 26 U.S. Code 199A – Qualified Business Income For 2026, it’s straightforward if your total taxable income is below $201,750 ($403,500 for married filing jointly). Above those thresholds, limitations based on wages paid and capital assets phase in, and service-based fields like law, health care, and consulting face further restrictions. This deduction reduces income tax only, not self-employment tax.
Net Operating Losses
A negative bottom line means a net loss. Under Section 172, you can carry a net operating loss forward to offset taxable income in future years. For losses arising after 2017, the deduction is capped at 80% of taxable income in any carryforward year, and the unused portion carries forward indefinitely.15Office of the Law Revision Counsel. 26 USC 172 – Net Operating Loss Deduction
Reading the Result
A positive bottom line means the business earned a net profit. The useful insight comes from comparing that number against prior periods and against gross revenue. A business generating $500,000 in revenue but only $15,000 in net income has a 3% profit margin, which leaves almost no room for a slow quarter or an unexpected expense.
Review your P&L monthly, even if you only file taxes annually. The value isn’t in the final number alone. It’s in spotting an expense category climbing faster than revenue while you can still adjust, rather than discovering the trend at tax time.