Updated October 19, 2026. Quick answer: Publication 334 is the IRS general guide for sole proprietors and independent contractors. It covers business taxes, accounting methods, business income, cost of goods sold, expenses and net profit. This edition is the one “For use in preparing 2025 Returns”.
Quick reference
| Item | As the IRS publication states it |
|---|---|
| Net earnings from self-employment that trigger filing a return (Income Tax) | $400 or more |
| Self-employment tax rate for 2025 (Self-Employment Tax) | 15.3% |
| Social security part of the rate (Self-Employment Tax) | 12.4% |
| Medicare part of the rate (Self-Employment Tax) | 2.9% |
| Earnings subject to the social security part in 2025 (Self-Employment Tax) | first $176,100 |
| Tax owed that generally calls for estimated payments (Income Tax) | $1,000 or more |
| Maximum section 179 deduction during 2025 (Business Expenses) | $2,500,000 |
What the publication covers
The introduction says “This publication provides general information about the federal tax laws that apply to you if you are a self-employed person or a statutory employee.” “This publication does not cover the topics listed in the following table.” The table that follows points elsewhere for corporations, farming, partnerships, rental activity and S corporations, among others.
On who is self-employed, it says “You are a self-employed person if you carry on a trade or business as a sole proprietor or an independent contractor.”
Chapters and parts in plain words
The first part covers filing and paying business taxes: identification numbers, income tax, estimated tax, self-employment tax, employment taxes, excise taxes and information returns. Next come accounting periods and methods (cash, accrual and combination, plus inventories and the uniform capitalization rules) and dispositions of business property.
The later parts cover general business credits, business income, how to figure cost of goods sold, and business expenses. The expense list includes car and truck expenses, depreciation, employees’ pay, insurance, interest, legal and professional fees, pension plans, rent, taxes, travel and meals, and business use of your home. The final part covers figuring net profit or loss and self-employment tax.
Worksheets, tables and charts inside
The publication opens with “Table A. What You Need To Know About Federal Taxes”, a list of questions with the chapter that answers each. It also walks through Schedule C cost of goods sold lines and a gross profit test.
On this site, see Schedule C (Form 1040), Schedule SE (Form 1040), Form 4562 and the home office deduction.
The figures that matter
On filing, the IRS publication says “You have to file an income tax return for 2025 if your net earnings from self-employment were $400 or more.” “For calendar-year 2025, Form 1040 or 1040-SR is due by April 15, 2026.”
On estimated tax, it says “You generally have to make estimated tax payments if you expect to owe taxes, including self-employment tax (discussed later), of $1,000 or more when you file your return.”
On self-employment tax, it says “The 2025 SE tax rate on net earnings is 15.3% (12.4% social security tax plus 2.9% Medicare tax).” “Only the first $176,100 of your combined wages, tips, and net earnings in 2025 is subject to any combination of the 12.4% social security part of SE tax, social security tax, or the Tier 1 part of railroad retirement tax.”
On equipment, it says “The maximum amount you can elect to deduct during 2025 is generally $2,500,000.” On small purchases, it says “If you don’t have an applicable financial statement, you may use the de minimis safe harbor to deduct amounts paid for tangible property up to $2,500 per item or invoice.”
Where to go next
For estimated payments, see Form 1040-ES and the estimated tax worksheet. For the tax itself, see Schedule SE. For payments to contractors, see Form 1099-NEC box 1.
Where this comes from
The IRS page About Publication 334 opens with “This publication contains general information about the federal tax laws that apply to small business owners who are sole proprietors and to statutory employees.” It links the PDF and eBook editions and the earlier revisions of the publication.
This page describes the web edition of Publication 334 (2025), Tax Guide for Small Business, as served on irs.gov on October 19, 2026. The IRS can revise a publication after we read it, and the IRS page controls. General information, not tax or legal advice.
Common mistakes
- Thinking a part-time side business is not self-employment. The IRS publication says “You do not have to carry on regular full-time business activities to be self-employed.”
- Thinking a business must turn a profit. The publication says “You do not need to actually make a profit to be in a trade or business as long as you have a profit motive.”
- Filing Schedule C for a business a married couple owns together. The publication says “If you and your spouse jointly own and operate an unincorporated business and share in the profits and losses, you are partners in a partnership, whether or not you have a formal partnership agreement.”
- Reading the wage base as a cap on all self-employment tax. The publication says “All of your combined wages, tips, and net earnings in 2025 are subject to any combination of the 2.9% Medicare part of SE tax, Medicare tax, or the Medicare part of railroad retirement tax.”
Related: IRS publications by number, Schedule C (Form 1040), Schedule SE (Form 1040), Form 1040-ES, Form 4562, Home office deduction, and Form 1099-NEC box 1.
Sources
- IRS, Publication 334 (2025), Tax Guide for Small Business (irs.gov): https://www.irs.gov/publications/p334
- IRS, About Publication 334 (irs.gov): https://www.irs.gov/forms-pubs/about-publication-334
Read from the IRS pages linked above on October 19, 2026. General information, not tax or legal advice. The IRS publication and the instructions for your own form control, and your own facts decide the outcome.