What an invoice is and why you need one
An invoice is a document that tells someone they owe you money and how to pay it. It lists what you sold or what work you did, the amount owed, when payment is due, and where to send the money. If you are a freelancer, small business owner, or contractor, sending an invoice is how you formally request payment and create a record both you and your customer can refer to.
An invoice is different from a receipt — a receipt proves payment already happened, while an invoice requests it. Invoices protect you because they document the debt, establish a paper trail for taxes, and give you grounds to follow up if payment is late. For your customer, an invoice is often required before they can process payment through their own accounting system.
You do not need special software to create an invoice. A spreadsheet, a Word document, or a PDF template will work. What matters is that the invoice contains the right information and reaches the person who authorized the work.
Key Takeaways
- An invoice must include your name and contact details, the customer's name, a description of the work or product, the amount owed, the due date, and your payment instructions.
- Send the invoice as soon as the work is complete or the product is delivered, not weeks later, so payment can be processed quickly.
- Include a unique invoice number and the date you issued it so both you and the customer can track it in your records.
- Specify your payment method — bank transfer, check, credit card, PayPal, or another option — and provide the exact details the customer needs to pay you.
- Follow up in writing if payment does not arrive by the due date, and keep copies of all invoices and payment records for tax purposes.
What information must go on an invoice
Start with your details at the top: your name or business name, your address, your phone number, and your email. The customer needs to know who they are paying and how to reach you if they have questions.
Next, add the customer's information: their name, company name (if applicable), and mailing address. This tells them the invoice is for them and gives you a record of who owes you money.
Then list the work or product: describe what you did or sold in enough detail that both you and the customer remember what the invoice covers. Instead of "consulting," write "website strategy consultation, 3 hours, January 15–17." Instead of "materials," list "50 custom printed business cards, 16 pt cardstock, matte finish."
Include the amount owed, the due date (for example, "due within 30 days" or "due by February 15"), and your payment instructions. Payment instructions mean the method and the details: "Pay by bank transfer to [your bank name], account [number]" or "Pay by check, made out to [your name], mailed to [your address]" or "Pay via PayPal to [your email]." Do not assume the customer knows how to pay you.
Add an invoice number (you can use 001, 002, 003, or any system that makes sense to you) and the date you issued the invoice. These help you and the customer track it.
How to create and format an invoice
You can use a spreadsheet (Google Sheets, Excel), a word processor (Google Docs, Word), or a free template from sites like Wave, Square Invoices, or Canva. If you send only a few invoices per year, a simple document is fine. If you send many, a template or free invoicing software saves time and ensures you do not forget information.
Format the invoice so it is easy to read: use a clear font, leave white space, and organize information in sections. Put your details and the invoice number at the top, the customer's details below that, then a table or list of what you are charging for, then the total amount due and payment instructions at the bottom.
If you are charging tax (sales tax, GST, or VAT depending on your location), add a line for it before the total. If you are offering a discount, show the original amount, the discount, and the final total. Transparency about the math builds trust.
Save the invoice as a PDF before sending it. A PDF looks the same on any device and cannot be accidentally edited by the recipient.
When and how to send the invoice
Send the invoice as soon as the work is complete or the product is delivered. Do not wait weeks — the sooner the customer receives it, the sooner they can process payment. If you are billing for ongoing work (like a monthly retainer), send the invoice on the same day each month.
Email is the standard method. Attach the PDF invoice to an email with a clear subject line: "Invoice #001 for [customer name]" or "Invoice for website design services." In the email body, write a brief note: "Hi [name], attached is the invoice for the work completed on [date]. Payment is due by [date]. Please let me know if you have any questions." Keep the tone professional but friendly.
If the customer prefers a different method — mailing a printed copy, uploading it to their accounting portal, or sending it through a specific invoicing platform — do what they ask. Some large companies require invoices through their vendor portal or procurement system.
Keep a copy of every invoice you send, along with the date and method you used to send it. This protects you if a payment dispute arises later.
What to include in your payment instructions
Be specific about how the customer should pay you. "Bank transfer" is not enough — include your bank name, account number, routing number (in the US), and the name the account is registered under. If the customer's bank is in a different country, you may also need your SWIFT code or IBAN.
If you accept checks, write the exact name the check should be made out to and the mailing address where they should send it. Include a note about how long checks typically take to clear (usually 3 to 5 business days after the customer mails it).
If you use PayPal, Stripe, Square, or another payment processor, include the email or link the customer should use. If you accept credit card payments, mention that and note any processing fee (if you charge one).
If you offer a discount for early payment — for example, 2% off if paid within 10 days instead of 30 — state it clearly on the invoice. This can speed up payment.
Following up when payment is late
If payment does not arrive by the due date, send a polite follow-up email within a few days. Reference the invoice number and due date, and ask whether the customer received it or has questions. Many late payments are simply forgotten or stuck in someone's inbox.
Keep the tone neutral: "Hi [name], I wanted to check in on invoice #001, which was due on [date]. Have you had a chance to process it? Please let me know if you need anything from me." Do not assume the customer is avoiding you.
If you still have not received payment after 7 to 10 days past the due date, send another email. This time, be more direct: "Invoice #001 is now [number] days overdue. Please send payment by [new date] or contact me to discuss payment arrangements."
Keep copies of all follow-up emails. If the customer continues to ignore you, you have a record of your attempts to collect. Some small business owners use a late-payment fee (for example, 1.5% per month on the overdue balance) — if you plan to do this, state it on the invoice before you send it, not after payment is late.
Payment methods and how long each takes
| Payment Method | How Long It Takes | What You Need to Provide |
|---|---|---|
| Bank transfer (ACH, in the US) | 1 to 3 business days | Your bank name, account number, routing number, account holder name |
| Wire transfer | Same day to 1 business day | Your bank name, account number, routing number, SWIFT code (if international) |
| Check by mail | 3 to 7 days (mail time) plus 3 to 5 days (clearing) | Your name, mailing address, and the name the check should be made out to |
| PayPal or similar service | 1 to 3 business days (to your bank account) | Your PayPal email or account link |
| Credit card | 1 to 3 business days | Your Stripe, Square, or other processor account link |
Keeping records for taxes and disputes
Save every invoice you send and every payment confirmation you receive. Organize them by year and customer. These records prove what you earned and when, which you need for tax filing. They also protect you if a customer later claims they never received an invoice or paid you.
If a customer pays by check, note the check number and date on your copy of the invoice. If they pay by bank transfer, save the confirmation email or receipt showing the transaction ID and amount. If they pay through PayPal or another processor, download the transaction record.
If a customer disputes a payment — for example, they claim they paid you but you never received it — you can show your records to your bank or payment processor to investigate. Without documentation, you have no proof.
Frequently Asked Questions
Can I send an invoice after I have already been paid?
Yes. If a customer paid you before you sent an invoice, you can still send one for your records and theirs. Mark it clearly as "paid" and include the payment date and method. This creates a complete record for both of you.
What if a customer refuses to pay?
Send a final written demand (email is fine) stating the amount owed, the invoice number, and a deadline for payment — usually 10 to 30 days. Keep a copy. If they still do not pay, you can pursue small claims court (the process and limits vary by state) or hire a collection agency, though both cost money and take time. For future customers, consider requiring a deposit or payment upfront for large projects.
Do I need to charge sales tax on my invoice?
It depends on your location, the type of work, and whether the customer is a business or individual. In the US, sales tax rules vary by state. Some services are taxed, others are not. Check your state's tax authority website or ask an accountant. If you are unsure, include a line on the invoice so you can add tax if needed.
What should I do if a customer says they never received my invoice?
Resend it immediately and ask them to confirm receipt. If you sent it by email, ask them to reply to confirm they got it. If they claim email is unreliable, offer to mail a printed copy or upload it to a shared folder they can access. Keep a record of every time you send it.
Can I use invoicing software instead of creating my own?
Yes. Free options like Wave, Square Invoices, and Zoho Invoice let you create, send, and track invoices automatically. They can also send payment reminders and accept online payments. If you send invoices regularly, software saves time and reduces mistakes. For occasional invoices, a simple template works fine.