There is no federal invoice form in the United States, so you design your own. IRS Publication 583 lists invoices among the documents that support your gross receipts and says that, except in a few cases, the law does not require any specific kind of records. A good invoice has two jobs: let your client pay without questions, and leave you a clean record. That means who is billing whom, for what, how much, when it is due and how to pay, plus a sales tax line if your state taxes what you sell.
Invoice field checklist
| Field | Status | What to put |
|---|---|---|
| Your business name and contact details | Always | The name that matches your bank account and Form W-9 (your own name, or your DBA), plus address, email and phone. |
| Client name and billing address | Always | The legal name of whoever pays, plus an accounts-payable email or purchase order number if their process needs one. |
| Invoice number | Always | A unique number that is never reused (see numbering below). |
| Invoice date, and service date or period | Always | The date you issue it and the date or period of the work or delivery. |
| Description | Always | Specific enough to match your quote or contract: what was done, where, and when. |
| Quantity, rate and line amount | Always | Hours times rate, or units times price, so the client can check the math. |
| Subtotal and discounts | Always | Show a discount as its own line instead of lowering the price silently. |
| Sales tax | Where it applies | A separate line with rate and amount, and a clear mark on which items are taxable. |
| Total due | Always | One number in US dollars, with any deposit already paid subtracted. |
| Due date and payment terms | Always | A calendar date such as "Due March 15", not only "Net 30". |
| How to pay | Always | The methods you accept and where to send payment: a payment link, bank transfer details, or who a check is payable to. |
| Late fee or deposit terms | Only if agreed | Terms the client already accepted in a quote or contract. Whether a late fee is enforceable varies by state. |
| Your Social Security number | Leave it off | If a client needs your taxpayer ID, it will ask for a Form W-9 (see the last section). |
The Status column is practical guidance, not an IRS rule. The one field a law can require is the sales tax line, and that depends on your state. Source for the recordkeeping rule: IRS Publication 583 (rev. December 2024).
Numbering that keeps your books clean
Use one running sequence for the whole business, such as 2026-001, 2026-002, 2026-003. Never reuse a number and never delete an invoice. If you made a mistake, issue a corrected invoice or a credit note that references the original, and keep both. A gap in your numbers is a question you will have to answer later, and a duplicate number is a payment that gets applied to the wrong job.
The same habit helps with sales tax records. New York, for example, tells sales tax vendors to keep a true copy of each sales slip or invoice, to date every record and to keep them in good order, and says that if you do not give the buyer a written document you need a detailed daily record of sales instead (New York Tax Department).
Payment terms, and when income counts
Agree on terms before the work starts, put them in your quote or contract, then repeat them on the invoice. Common choices are due on receipt, or due in 15 or 30 days. Send the invoice as soon as the work is delivered, and for large jobs invoice a deposit first. Say plainly what happens when payment is late, and only if the client has agreed to it.
An invoice date does not decide the tax year. Under the cash method, Publication 583 says you report income in the tax year you receive it. Under the accrual method you report it in the year you earn it. If inventory is needed to account for your income, you generally must use accrual, with an exception for certain small businesses. Worked example: you invoice $1,500 on December 28 and the client pays on January 10. A cash-method business reports that $1,500 on the return for the year of January 10, while an accrual-method business reports it for the year it was earned. Ask a tax professional which method applies to you.
The sales tax line
Sales tax is set by states, and sometimes cities and counties, so whether you charge it and how it must appear depends on where you sell and what you sell. Three state agencies show the pattern:
- New York says you must always separately state the amount of sales tax due on the invoice or receipt, and the document must identify which items are taxable when you sell both taxable and nontaxable items.
- Washington requires sellers to separately state the retail sales tax on invoices. If an invoice does not list it, the Department of Revenue assumes the tax was not paid, and the buyer may owe use tax directly (Washington DOR).
- Texas generally requires a separate statement too. The exception is a written statement to customers that tax is included in the price, together with a prominent sign. The seller is responsible for collecting and paying the correct amount (Texas Comptroller).
Other states differ, so ask your state revenue department what is taxable for your business and when you must register. Registering with the state is its own step, and the registration guide covers the order.
Keeping the records
Publication 583 lists invoices next to cash register tapes, bank deposit slips, receipt books, credit card charge slips and Forms 1099-NEC as the documents behind your gross receipts. It also says to keep your business account separate from your personal checking account. Practical setup:
- Save a copy of every invoice you issue, paid or not. Result: you can show what you billed in any period.
- Write the invoice number in your deposit log or accounting software when the money arrives. Result: each deposit ties to one invoice, so unpaid ones stand out.
- Take payment into the business account. Whatever method you use, including a card reader or payment link or an instant payment, the deposit should land in one place.
How long to keep them depends on your situation. The IRS table in Publication 583 gives three years for most returns, six years if you left out income of more than 25% of the gross income on your return, and an unlimited period if you filed no return or a fraudulent one. State sales tax rules can add their own period; New York, for example, asks vendors for at least three years. See the sole proprietorship guide for the rest of a sole proprietor's records.
When a client asks for a Form W-9
A client that pays you for services in the course of its business generally files Form 1099-NEC once payments reach the threshold, which is $2,000 for payments made after December 31, 2025 (it was $600 before) (IRS). To file it, the client needs your name and taxpayer identification number, which it requests on Form W-9. Return it promptly: the IRS instructions for requesters say backup withholding applies when a payee does not furnish a TIN, at a rate of 24% of reportable payments (IRS). On the form, a business, trade or DBA name goes on line 2. Use the current version from irs.gov, because forms are revised.
Thresholds, forms and state rules change, so confirm them on irs.gov and with your state before you rely on them.
Frequently asked questions
Is there a legal requirement to send invoices?
No federal rule sets an invoice format. IRS Publication 583 says the law does not require any specific kind of records except in a few cases, but you must keep records that support your income. Some states do require sales tax to be shown separately on invoices, so check yours.
What should an invoice number look like?
Any unique, running sequence works, for example 2026-001, 2026-002. The point is that you never reuse a number and can account for every invoice you issued.
How long should I keep invoices?
The IRS table in Publication 583 gives three years for most returns and six years if you omitted income over 25% of the gross income shown on your return. State sales tax rules may add their own period, such as New York's three-year minimum for vendors.
Do I charge sales tax on every invoice?
Not necessarily. Whether your goods or services are taxable, and whether you must register to collect, depends on your state. If you do collect, New York, Washington and Texas all expect it to be stated separately, so ask your state revenue department.
What is a Form W-9 and when will a client ask for it?
It is the IRS form a payer uses to request your name and taxpayer identification number so it can file an information return such as Form 1099-NEC. Clients usually ask when they first set you up as a vendor.
Sources: IRS Publication 583, Starting a Business and Keeping Records (rev. December 2024) · IRS, Form 1099-NEC and independent contractors · IRS, Instructions for the Requester of Form W-9 (rev. March 2024) · IRS, Form W-9 · New York State Tax Department, Recordkeeping requirements for sales tax vendors · Washington Department of Revenue, Sales tax not listed on the invoice · Texas Comptroller, Sales and use tax FAQ: collection
