US Small Business Taxes & Deductions (IRS Guides)
The IRS's own guides for sole proprietors and small businesses: business income and expenses (Pub 334), starting a business and record keeping (Pub 583), travel, meals, gift and car expenses (Pub 463), home office deduction (Pub 587) and depreciation, Section 179 and bonus depreciation (Pub 946). For entrepreneurs, freelancers and tax preparers. Curated by Kopik from public sources: Internal Revenue Service (US public domain).
Posez votre question
Compte gratuit requisLes réponses sont rédigées par un modèle de langage à partir des seuls documents de cette base, avec leurs sources numérotées. Elles peuvent être inexactes et ne constituent pas un conseil juridique, médical ou financier : vérifiez les sources avant toute décision importante.
This assistant answers federal tax questions for sole proprietors, freelancers and small business owners in the United States. Its answers come from five IRS publications: Pub 334 (Tax Guide for Small Business), Pub 583 (Starting a Business and Keeping Records), Pub 463 (Travel, Gift, and Car Expenses), Pub 587 (Business Use of Your Home) and Pub 946 (How To Depreciate Property). It is useful for anyone preparing a Schedule C return, and for tax preparers who want to check a rule quickly.
Who has to file and which forms apply
According to Pub 334, you have to file an income tax return for 2025 if your net earnings from self-employment were $400 or more. If they were less than $400, you may still have to file if you meet another filing requirement listed in the Instructions for Form 1040.
Sole proprietors report business income and expenses on Schedule C (Form 1040). Spouses who run a qualified joint venture each file a separate Schedule C and a separate Schedule SE.
You need an Employer Identification Number (EIN) in addition to your SSN if you pay wages to one or more employees or file pension or excise tax returns. Pub 583 notes that if you apply by mail with Form SS-4, you should file it at least 4 weeks before you need the EIN.
You can apply for an EIN online at IRS.gov/EIN; if your principal business location is in the United States or U.S. territories, the EIN is issued immediately once the application information is validated. If you pay nonemployee compensation, Pub 334 lists Form 1099-NEC as due to the IRS by January 31, even if you file electronically.
Self-employment tax and estimated payments
Self-employment (SE) tax is a social security and Medicare tax for individuals who work for themselves. Pub 334 gives the rate as 15.3% of net earnings: 12.4% social security tax plus 2.9% Medicare tax.
You can deduct one-half of your SE tax as an adjustment to income on line 15 of Schedule 1 (Form 1040).
Because no employer withholds tax for you, you generally have to make estimated tax payments if you expect to owe tax, including self-employment tax, of $1,000 or more when you file your return.
You must pay SE tax and file Schedule SE (Form 1040) if your net earnings from self-employment, excluding church employee income, were $400 or more. You must also pay SE tax if you had church employee income of $108.28 or more.
What counts as a deductible business expense
Pub 334 defines the two basic tests. An ordinary expense is one that is common and accepted in your field of business. A necessary expense is one that is helpful and appropriate for your business; it does not have to be indispensable.
Expenses you incur before you actually begin operations are business start-up costs, such as advertising, travel, surveys and training. Pub 583 explains that you can elect to deduct up to $5,000 of start-up costs and up to $5,000 of organizational costs. Each $5,000 deduction is reduced by the amount your costs exceed $50,000, and any remaining costs must be amortized.
The costs of a particular asset, such as machinery or office equipment, are generally capital expenses that you recover through depreciation rather than deducting all at once. The assistant can explain how Pub 946 handles these assets, and how Pub 334 treats everyday expenses like legal and professional fees directly related to operating your business.
Keeping records the IRS will accept
Pub 583 asks you to keep supporting documents for your business transactions, including sales slips, paid bills, invoices, receipts, deposit slips and canceled checks.
Records that support income or deductions must be kept until the period of limitations for that return runs out. In most cases that period is 3 years. It is 6 years if you fail to report income that is more than 25% of the gross income shown on the return, and it is not limited if you file a fraudulent return or do not file at all.
If you have employees, keep all employment tax records for at least 4 years after the date the tax becomes due or is paid, whichever is later.
Questions fréquentes
Do I have to file a tax return if my side business earned very little?
Pub 334 says you must file if your net earnings from self-employment were $400 or more. Below that amount, you may still have to file if you meet another filing requirement in the Instructions for Form 1040. The assistant can walk you through how net earnings are figured.
What is the self-employment tax rate?
The rate on net earnings is 15.3%, made up of 12.4% for social security and 2.9% for Medicare. You report it on Schedule SE and can deduct one-half of it as an adjustment to income on Schedule 1 (Form 1040).
When do I need to pay estimated tax?
Generally, you have to make estimated tax payments if you expect to owe tax, including self-employment tax, of $1,000 or more when you file. Pub 334 and Pub 583 both cover this rule for sole proprietors.
Can I deduct costs I paid before my business opened?
These are business start-up costs. You can elect to deduct up to $5,000 of them, reduced by the amount your start-up costs exceed $50,000, and amortize the rest. The same rule applies separately to organizational costs.
How long should I keep my business receipts?
Keep records until the period of limitations for the return runs out, which is usually 3 years. It is 6 years if you left out income exceeding 25% of the gross income shown, and employment tax records must be kept at least 4 years.
Do I need an EIN as a sole proprietor?
Pub 334 says you must have an EIN if you pay wages to one or more employees or file pension or excise tax returns. In that case, include it along with your SSN on Schedule C as instructed. You can apply online at IRS.gov/EIN.
Intégrer / API / MCP
Branchez cette base à Claude, Cursor, ChatGPT ou votre propre application. Chaque requête API ou MCP coûte 0,10 €, débitée de votre crédit Kopik (non facturée si rien n'est trouvé). Il vous faut une clé API : créez-la depuis votre tableau de bord.
MCP pour vos agents
Adresse du serveur MCP de cette base (outils ask_base et search_base) :
https://kopik.io/api/mcp?base=us-small-business-tax-irs-guideClaude Code, Cursor et autres clients
claude mcp add --transport http kopik-us-small-business-tax-irs-guide "https://kopik.io/api/mcp?base=us-small-business-tax-irs-guide" --header "Authorization: Bearer kpk_…"{
"mcpServers": {
"kopik-us-small-business-tax-irs-guide": {
"url": "https://kopik.io/api/mcp?base=us-small-business-tax-irs-guide",
"headers": {
"Authorization": "Bearer kpk_…"
}
}
}
}API REST pour vos applications
mode vaut "answer" (réponse rédigée + sources) ou "passages" (passages bruts seulement). Ajoutez un maxPriceCents facultatif pour plafonner le prix : si la base coûte plus cher, l'appel est refusé sans rien débiter.
curl -X POST https://kopik.io/api/v1/bases/us-small-business-tax-irs-guide/query \
-H "Authorization: Bearer kpk_…" \
-H "Content-Type: application/json" \
-d '{"question": "Votre question ici", "mode": "answer"}'Pour commencer
- Créez une clé dans votre tableau de bord et rechargez votre crédit.
- Remplacez
kpk_…par votre clé. - Tout le détail (réponses, erreurs, exemples JS et Python) : documentation développeurs.