How to write an invoice.

The short version: say who it's from and who it's to, give it a unique number and a date, list what you did with prices, add sales tax only if you're registered to collect it, show the total and when it's due, and say how to pay you. Keep a copy.

What to put on an invoice

There's no single federal invoice format in the US. A clear invoice that your customer (and you, at tax time) can rely on usually has:

1. The word "Invoice" and a unique invoice number.
2. Your business name and contact details (email or phone).
3. Your customer's name and address.
4. The invoice date, and the due date or payment terms.
5. What you did or supplied, line by line: hours × rate for labor, or a flat fee, plus materials or items with their prices.
6. A subtotal, any sales tax as its own line, and the total due.
7. How to pay you: Zelle, bank transfer, check payable to…, and so on.

Some industries and states have their own extra rules (for example, auto repair and home improvement). If you're in a licensed trade, check with your state licensing board.

Invoice numbers

Give every invoice its own number and never reuse one. Any system works as long as it's consistent: INV-0142, or a date plus a counter like INV-260926-3150. Unique numbers make it easy to match payments, answer "which invoice is this for?", and keep clean records.

Due dates and payment terms

Put a clear due date on the invoice rather than only a phrase. "Net 14" means payment is due 14 days after the invoice date; "Net 30" means 30 days. "Due on receipt" means now. Whatever you choose, agree it with your customer up front, and write the actual date on the invoice so there's no argument about it.

Sales tax on an invoice

• There's no federal sales tax. Sales tax is a state and local tax.
• Five states have no statewide sales tax: Alaska, Delaware, Montana, New Hampshire and Oregon. Alaska still lets local areas charge one.
• Whether you must charge it depends on your state and on what you sell. Many states tax goods; the rules for services vary a lot from state to state.
• You generally need to register with your state (often called a sales tax permit or seller's permit) before you collect sales tax from customers.
• Selling into other states? Since the Supreme Court's 2018 Wayfair decision, states can require out-of-state sellers to collect once their sales into the state pass a threshold. Thresholds differ by state.
• On the invoice: if you do charge sales tax, show it as its own line so your customer can see what's tax and what's your price.

Invoice & Quote never works out sales tax for you, because the right answer depends on your state, your city and what you sell. You enter the dollar amount and it appears as its own line.

Getting paid by businesses: W-9 and 1099

If you invoice another business as an independent contractor, they may ask you for a Form W-9 (your name and taxpayer ID). For payments made from 2026 onward, a business generally has to report payments to a non-employee on Form 1099-NEC once they reach $2,000 in a year. That's up from the $600 limit that applied for decades. Your invoices don't replace any of this, but they're the record that backs it up.

Keep your records

The IRS treats invoices as supporting documents for your income and expenses. Generally, keep records for 3 years from when you file the return they support, and longer in some situations (for example, 7 years for a bad-debt deduction, or 6 years if income is substantially underreported). With a free Invoice & Quote account, every invoice you make is kept in your history.

Common mistakes

• No due date, just "please pay soon".
• Reusing an invoice number.
• Lumping everything into one line, so the customer can't see what they're paying for.
• Adding sales tax without being registered to collect it.
• Forgetting to say how to pay you.

See a sample invoice (PDF)

Sources

• IRS: How long should I keep records?
• IRS: Instructions for Forms 1099-MISC and 1099-NEC (the $2,000 threshold for payments after December 31, 2025)
• IRS: About Form W-9
• U.S. Small Business Administration: Apply for licenses and permits (sales tax registration)
• Tax Foundation: State and local sales tax rates
• Sales Tax Institute: Economic nexus state guide (post-Wayfair thresholds)
• Federation of Tax Administrators: Find your state's tax agency

General information for US businesses, not tax or legal advice.