How to write an invoice (US guide)

If you're freelancing or running a small business in the US, a well-written invoice is your ticket to getting paid on time. It's also your record for tax season. Getting it right from the start saves you headaches in April.

Here's exactly what to include, what the IRS expects, and how to avoid the mistakes that delay payment.

What must appear on a US invoice

There's no single federal law dictating invoice format, but every invoice you send should include these details:

• Your business name and contact details — legal name (or DBA), address, phone number, email
• Your client's name and address
• A unique invoice number — sequential, no gaps (INV-001, INV-002, etc.)
• The invoice date — the date you issue it
• A description of the goods or services — clear enough that your client knows exactly what they're paying for
• The amount due — unit price, quantity, and total for each line item
• The total amount — including any applicable sales tax
• Payment terms — when you expect to be paid (e.g., "Net 30" means within 30 days)
• Your payment details — bank account (routing and account number), or a payment link

If you're registered for sales tax in your state, you must include your sales tax ID and show tax separately from the net amount.

Invoice numbering

While the IRS doesn't mandate sequential numbering like HMRC does in the UK, consistent numbering is a best practice. It makes record-keeping easier, simplifies audits, and looks professional.

Use any format — INV-001, 2026-001, or ACME-0001 — as long as there are no duplicates.

Coinvoice assigns invoice numbers automatically using your chosen prefix, so you never have to track this manually.

What to write in the description

Vague descriptions cause payment delays. "Consulting services" tells your client nothing. Be specific:

Bad: "Design work — $500"

Good: "Website redesign for acme.com — homepage layout, 3 inner page templates, mobile responsive. Delivered March 15, 2026 — $500"

The more specific your description, the harder it is for a client to dispute or delay payment. Include dates, deliverables, and any agreed reference numbers.

Setting payment terms

Payment terms tell your client when you expect to be paid. Common options in the US:

• Due on receipt — payment expected immediately
• Net 15 — within 15 days
• Net 30 — within 30 days (the most common)
• Net 60 — within 60 days (common with larger companies)

If you don't specify payment terms, there's no automatic federal default like the UK's 30-day rule. This makes it even more important to state your terms clearly on every invoice.

State your terms clearly on the invoice. Don't bury them in small print.

Sales tax considerations

Sales tax in the US varies by state (and sometimes by city and county). Unlike VAT, sales tax generally applies to goods, not services — but some states tax certain services too.

Key rules:

• You must collect sales tax if you have nexus (a business presence) in a state that imposes it
• Five states have no sales tax: Alaska, Delaware, Montana, New Hampshire, and Oregon
• Remote sellers may have nexus through economic activity (post-Wayfair ruling, 2018)

If sales tax applies, show it as a separate line item on your invoice. Include your state tax registration number.

When in doubt, consult a CPA or use your state's Department of Revenue website.

Common invoicing mistakes

1. Not sending the invoice promptly. Send your invoice as soon as the work is delivered. Every day you delay is a day added to your payment timeline.

2. Missing or wrong details. A wrong address, missing invoice number, or incorrect amount gives your client a reason to "query" the invoice — which means weeks of back-and-forth before you get paid.

3. No payment link. If your client has to look up your routing number, find a checkbook, or set up a wire transfer, you've added friction. Include a direct payment link on every invoice. Coinvoice invoices include a one-click "Pay Now" button that accepts card and PayPal.

4. Not following up on overdue invoices. If your invoice is overdue, send a polite reminder. Unlike the UK, the US has no statutory interest law for commercial debts, but your contract can specify late fees.

5. Inconsistent formatting. Using a different layout every time looks unprofessional and makes record-keeping harder. Use a consistent invoice template or invoicing tool.

W-9 and 1099 considerations

If you're a US freelancer, your clients may ask for a W-9 form before they pay you. This provides your taxpayer identification number (SSN or EIN) so they can issue a 1099-NEC at year end.

Key points:

• Clients must issue a 1099-NEC if they pay you $600 or more in a calendar year
• You're responsible for reporting all income, even if you don't receive a 1099
• Keep copies of all invoices — they're your primary income records for Schedule C

How long should I keep invoices?

The IRS recommends keeping records for at least 3 years from the date you filed your return. If you underreported income by more than 25%, keep records for 6 years. Many accountants recommend keeping records for 7 years to be safe.

Digital records are fine — you don't need paper copies.

Creating your first invoice

The fastest way to create a professional invoice is with a dedicated tool. You can use our free invoice generator to build and download a PDF right now, no account required.

If you want to send invoices by email, track payments, and get paid online, sign up for Coinvoice — it's free for up to 5 active clients with unlimited invoices.