How to Write an Invoice: Required Fields and a Free Template

An invoice is your request for payment and also your record of income. A clear invoice gets paid faster, and a complete one saves you trouble at tax time. This guide explains what to include and how to make it work.

What every invoice needs

If the client gave you a purchase order number, include it. Many accounting departments cannot pay without one.

Choose clear payment terms

Payment terms state how long the client has to pay. Common ones are:

• Due on receipt: payment is expected immediately.
• Net 15 or Net 30: payment is due 15 or 30 days after the invoice date.
• Deposit plus balance: for example, 50% upfront and 50% on delivery.

Shorter terms improve your cash flow. Larger companies often ask for Net 30 or Net 60, so negotiate the terms before starting the work and put them in your contract.

Invoice numbering

Use a consistent system, such as 2026-001, 2026-002 and so on. Do not reuse numbers or skip them without reason. A sequence makes it easy to find an invoice, spot missing payments and keep accurate books.

Sales tax

Whether you must charge sales tax on services depends on your state and the type of service. Many states do not tax most freelance services, but some do. Check with your state's revenue department before issuing invoices.

A free template

INVOICE #2026-001
Issue date: [date]        Due date: [date]

From:
[Your name or business]
[Address] | [Email] | [Phone]

Bill to:
[Client name or company]
[Contact person]
[Address]

Description                          Qty / Hours    Rate      Amount
Website design, homepage mockup       10            $75       $750.00
Revisions, round 2                     3            $75       $225.00

Subtotal:                                                    $975.00
Sales tax (if applicable):                                     $0.00
Total due:                                                   $975.00

Payment terms: Net 15
Pay by: bank transfer to [account details] or [payment link]
Late payments are subject to a [x]% monthly fee.

Thank you for your business.

Tips for getting paid faster

1. Send the invoice the day the work is delivered, or on the agreed milestone.
2. Use a PDF and keep the email short, with the due date and total in the first line.
3. Make payment easy by offering a link or a transfer instruction clients can copy.
4. Send a friendly reminder a few days before the due date.
5. Ask for a deposit on larger projects.

Keep your records

Save every invoice and the matching payment record. The IRS generally expects you to keep records that support your income and deductions for at least three years after you file the return that uses them.

Common mistakes

• Vague descriptions such as "services" without detail.
• No due date, which makes late payment hard to enforce.
• Sending invoices to the wrong contact and never confirming receipt.
• Forgetting to add the purchase order number.