You earned self-employment income this year — freelance work, a side business, a single-member LLC — and now the tax return staring back at you asks questions you have never had to answer before. What counts as business income? Which expenses are actually deductible? Do you owe quarterly estimated tax on top of everything else? The IRS wrote a free guide that answers all of it in plain language, updated every year, and most first-time Schedule C filers have never opened it.
That guide is Publication 334, Tax Guide for Small Business. It is written specifically for people who report profit or loss on Schedule C, and it walks the full journey from "what is business income" to "how do I pay self-employment tax." This article explains what is inside, who it is for, and how to use it without reading all hundred-plus pages.
What Publication 334 Is (and Who It Is For)
Publication 334 provides general information about the federal tax laws that apply to you if you are a self-employed person or a statutory employee. In practical terms, it is for you if any of these describe you:
- Sole proprietor. You own an unincorporated business by yourself and report its income and deductions on your personal return.
- Single-member LLC owner. Unless you elected corporate treatment, your LLC is disregarded for income tax purposes, which makes you a sole proprietor in the IRS's eyes and puts your numbers on Schedule C.
- Independent contractor or freelancer. If you carry on a trade or business as an independent contractor, you are self-employed even if you think of yourself as "just freelancing."
- Statutory employee. If your Form W-2 has a checkmark in box 13, you report wages and expenses on Schedule C rather than as an ordinary employee.
The guide is free, revised annually — the current edition covers the 2025 tax year — and it pairs with the Schedule C instructions the way a textbook pairs with a worksheet. The instructions tell you which line a number goes on; Publication 334 explains what the number means and which tax rules put it there.
How the Guide Is Organized: A Chapter Walkthrough
The publication has twelve chapters. You do not need all of them at once, but knowing what lives where turns it into a reference you can dip into for years.
Chapters 1–2: Paying Your Taxes and Choosing Your Accounting Method
Chapter 1, Filing and Paying Business Taxes, is the logistics chapter: which forms you file, when they are due, whether you need an Employer Identification Number, and what changes the moment you hire employees. It also covers estimated tax — the pay-as-you-go system that surprises almost every new freelancer. When no employer withholds for you, you generally pay income and self-employment tax in quarterly installments on Form 1040-ES, and this chapter explains how to figure them and what happens if you underpay.
Chapter 2, Accounting Periods and Methods, covers two decisions that shape your entire return. First, your tax year: most small businesses use the calendar year, but fiscal years are possible. Second, your accounting method: the cash method records income when you receive it and expenses when you pay them, while the accrual method records them when earned or incurred. Most sole proprietors start on cash because it is simpler and matches their bank statements, and the chapter explains the trade-offs plus the inventory rules that apply when selling products is an income-producing factor in your business.
Chapters 3–4: Selling Business Property and Claiming Credits
Chapter 3, Dispositions of Business Property, answers what happens when you sell, trade in, or retire a business asset — equipment, vehicles, or real property used in the business. Gains and losses here generally do not go on Schedule C at all; they flow to other forms, and the chapter routes you to the right one.
Chapter 4, General Business Credits, is the one most owners skip and should not. Credits reduce your tax dollar for dollar rather than merely reducing taxable income, and the chapter explains how the general business credit bundles individual credits together with carryforwards and carrybacks.
Chapters 5–7: Income, Cost of Goods Sold, and Gross Profit
Chapter 5, Business Income, defines what counts as income more broadly than most owners expect. Beyond sales of products and services, it covers bartering, canceled debt, recovered bad debts, and other receipts first-time filers often miss. It also lists items that are not income, so you do not pay tax on money that was never yours to begin with.
Chapters 6 and 7 work as a pair for anyone who sells goods. Chapter 6, How To Figure Cost of Goods Sold, walks through beginning inventory, purchases, labor, materials, and ending inventory — the calculation that turns "what I sold" into "what it cost me to sell it." Chapter 7, Figuring Gross Profit, subtracts that cost from gross receipts. Service businesses can skim this stretch; product businesses should read it twice, because COGS errors are among the most common Schedule C mistakes.
Chapter 8: Business Expenses — The Chapter You Will Revisit Most
Chapter 8, Business Expenses, is the heart of the guide and the longest chapter. It opens with the standard behind every deduction on your return: an expense must be both ordinary (common and accepted in your trade) and necessary (helpful and appropriate for your business). Everything after that applies the standard to specific categories:
- Business use of your home. The requirements for claiming a home office, including the simplified method versus actual expenses.
- Car and truck expenses. The standard mileage rate versus actual expenses, with the recordkeeping each method demands. For 2025 the standard rate is 70 cents a mile; for 2026 it rises to 72.5 cents.
- Depreciation and Section 179. How to spread equipment costs over recovery periods or expense them immediately. For 2025 the Section 179 limit rose to $2.5 million, phasing out once placed-in-service property exceeds $4 million, and 100% bonus depreciation returned for qualifying property acquired after January 19, 2025.
- Meals. Business meal deductions generally remain limited to 50% of the cost.
- Bad debts. Newly folded into this chapter after the IRS discontinued Publication 535, so uncollectible business debts now live alongside every other expense discussion.
- Expenses you cannot deduct. Just as valuable as the deductible list — personal expenses, most commuting costs, and other permanently off-limits items spelled out so you stop guessing.
Read this chapter once end to end, then treat it as your deduction dictionary for the rest of your business life.
Chapters 9–10: Your Bottom Line and Self-Employment Tax
Chapter 9, Figuring Net Profit or Loss, brings income and expenses together into the Schedule C bottom line — and explains what happens when the number is negative, including the excess business loss limitation computed on Form 461, which recent legislation made permanent.
Chapter 10, Self-Employment Tax, covers the 15.3% tax that funds Social Security and Medicare for people with no employer to split it with. Two numbers matter here: the maximum net earnings subject to the Social Security portion is $176,100 for 2025 and $184,500 for 2026, while the Medicare portion has no cap. If your net earnings cross those thresholds, only the Social Security slice stops — Medicare continues on every dollar.
Chapters 11–12: Your Rights and Where to Get Help
The final chapters cover your rights as a taxpayer and how to get more information — publications, forms, and IRS assistance channels. Skim them once so you know they exist; you will be glad you did the April you need them.
What Changed Recently: The Updates That Affect Your Next Return
Each edition opens with a "What's New" section, and the current one is unusually full. Beyond the mileage, Section 179, and self-employment threshold figures above, three changes deserve every Schedule C filer's attention:
- New deductions for tips and overtime — but not on Schedule C. Starting in 2025, qualifying workers may deduct up to $25,000 of tips and up to $12,500 of overtime pay ($25,000 for joint filers). Both deductions are claimed on Schedule 1-A, not on Schedule C, which is exactly the kind of placement detail that trips up filers who stop reading at the headline.
- Domestic research costs are expensible again. Beginning in 2025, you can deduct domestic research and experimental expenditures as current business expenses — or elect to capitalize and amortize them over 60 months or more. Builders and software founders should read this section before assuming the old capitalization rules still apply.
- Information reporting thresholds are moving. For payments made after 2025, the threshold for information reporting and backup withholding rises to $2,000, and the 20% qualified business income deduction is now permanent with higher income thresholds for its limitations.
Tax law moves every year, which is the real argument for bookmarking the guide rather than memorizing any single edition.
How to Use the Guide Without Reading 100 Pages
Nobody reads Publication 334 cover to cover, and you do not have to. Use this workflow instead:
- New business, first return? Start with chapters 1 and 2. Confirm your filing obligations, get your EIN sorted, decide cash versus accrual, and set up estimated tax before penalties teach you the lesson.
- Mid-year estimated tax panic? Jump to chapter 1's estimated tax section. It tells you how to compute the quarterly payments and which payment options exist.
- Wondering "can I deduct this?" Keep chapter 8 open. Search it for the expense category before you ask the internet — the IRS's own answer beats a stranger's every time.
- Bought equipment or a vehicle? Read the depreciation and car-expense sections before you file. Section 179, bonus depreciation, and the mileage-versus-actual choice are all elections with deadlines; after filing season, the favorable option may be gone.
- Received a notice? Chapters 9 through 11. Loss limitations, self-employment tax math, and your rights as a taxpayer live here.
One more habit multiplies the value of all five: keep records the guide would approve of. Publication 334 quietly assumes throughout that you can substantiate what you claim — receipts, mileage logs, and books that separate business from personal. The filers who dread April are rarely the ones who owe the most; they are the ones reconstructing twelve months of activity from memory.
Keep Your Schedule C Records Organized All Year
Every chapter of the guide points back to the same foundation: clear, contemporaneous records of your income and expenses. When your books already separate business from personal and every deduction traces to a receipt, filing Schedule C becomes transcription instead of archaeology. Beancount.io provides plain-text accounting that gives you complete transparency and control over your financial data — no black boxes, no vendor lock-in. Get started for free and see why developers and finance professionals are switching to plain-text accounting.
