How to Send an Invoice by Email

Who to send the invoice to

The most common invoicing mistake is sending to the wrong person. Your day-to-day project contact is rarely the person who processes payments. Before you raise your first invoice for any client, ask:

• Who is the correct person or department to receive invoices? (Often “accounts payable” or a finance contact)
• Is there a specific email address invoices must go to, or should they be submitted via a supplier portal?
• Do they require a purchase order (PO) number on the invoice before it can be processed?

Large companies in particular have strict accounts payable processes. An invoice sent to the wrong address can sit unprocessed for weeks before anyone notices. Finding out the correct recipient at the start of a project saves a lot of chasing later.

The right subject line

Your subject line should make it immediately obvious what the email contains and give the recipient enough information to find it later. A good formula:

Invoice [NUMBER] from [Your Name / Business Name] — [Project or Month] — due [Date]

For example: Invoice 047 from Jane Smith Design — Brand Refresh Project — due 15 October 2026

Including the invoice number and due date in the subject line means that when you follow up, the client can search their inbox and find both the original and your reminder in one thread. Avoid vague subjects like “Invoice” or “Payment due” — these are easy to overlook and harder to file.

What to write in the email

Keep the email body short. The invoice itself contains all the detail; the email just needs to introduce it. A good invoice email:

• Greets the recipient by name if you know it
• States what the invoice is for in one sentence
• Confirms the total amount and the due date
• Tells them how to pay (or points them to the invoice for details)
• Invites them to get in touch if they have any questions

Example:

Hi Sarah,

Please find attached Invoice 047 for the brand refresh project, totalling £2,400 (inc. VAT). Payment is due by 15 October 2026 via BACS transfer to the details on the invoice.

Do let me know if you have any questions.

Thanks,
Jane

There is no need to apologise for asking to be paid, add lengthy pleasantries, or repeat every line item from the invoice in the email body. Brief and professional is better than warm and wordy.

Attaching the invoice correctly

Always send your invoice as a PDF, not a Word document, Excel spreadsheet, or editable file. PDF files:

• Look the same on every device and in every email client
• Cannot be accidentally edited by the recipient
• Are universally accepted by accounting software
• Are suitable for HMRC record-keeping purposes

Name the file clearly: Invoice-047-JaneSmithDesign.pdf is better than invoice.pdf or doc1.pdf. A clear filename helps the client file it correctly on their end and helps you if you need to find it later.

If you are sending a large invoice (over £5,000, or to a new client) it is worth double-checking the invoice before you send it. Errors on invoices delay payment and undermine confidence in your professionalism.

Following up on unpaid invoices

Even well-organised clients miss invoices occasionally. A clear follow-up process helps you recover payment without damaging the relationship. A simple schedule:

• Three days before the due date: a brief, friendly reminder that payment is due shortly. This catches invoices that have been lost in inboxes before they actually become overdue.
• The day after the due date: a polite note that payment has not yet been received and asking when it will be made.
• Seven days overdue: a firmer follow-up referencing the invoice number, the original due date, and noting that statutory interest may apply.
• 14 or more days overdue: consider a formal written notice and review whether to pause further work for the client.

For ready-to-use templates for each of these stages, see the Chasing Late Invoices guide.

Keeping records

HMRC requires you to keep business records, including invoices, for at least five years after the Self Assessment deadline for the relevant tax year. This means keeping copies of every invoice you send and evidence that it was sent.

A few practical habits:

• Save a copy of every invoice PDF in an organised folder, with the invoice number in the filename
• Keep sent emails as a record of delivery and timing
• Note the date payment was received so you have a complete record of each invoice's lifecycle

If you use invoicing software, most of this is handled automatically. Sent invoices are stored with their dates, and payment status is updated when you record a payment.