The email around your invoice decides how fast it moves through your client’s approval process. This guide shows you how to send an invoice by email so it gets paid, with a subject line formula, four copy-paste templates, a worked example with the numbers checked, and a reminder schedule you can reuse every month.
Search intent: you have finished the work and want to send an invoice that a busy client, or their accounts team, can approve and pay without coming back to you with questions.
What should an invoice email include?
An invoice email needs a subject line with the invoice number and due date, a short body that names the work, the total owed and how to pay, and the invoice itself attached as a PDF. Add your payment details, a purchase order number if the client gave you one, and a clear request to confirm receipt.
Think of the email and the invoice as two separate jobs. The invoice is the formal record. It carries your name and address, the client’s details, a unique invoice number, the issue date, the due date, an itemised list of the work, any tax, and the total. If you are unsure about any of those fields, work through how to write an invoice step by step first.
The email is the delivery note. Its job is to get the invoice opened, forwarded to the right person, and paid. Accounts staff process dozens of invoices. They scan for four facts: who it is from, what it is for, how much, and when it is due. If they have to open the attachment to find any of those, you have added friction and delay.
One detail matters more than most freelancers realise: send the invoice to the person who approves payment, not only to the person who commissioned the work. On larger clients those are different people. Ask at the start of the job who invoices should go to, and whether they need a purchase order number quoted. An invoice without a required purchase order number can sit in a queue for weeks.
How do you send an invoice by email, step by step?
Create the invoice as a PDF, check the total, due date and payment details, then write a short email that repeats those three facts in the body. Attach the PDF, use a subject line with the invoice number, send it to the person who approves payment, and ask them to confirm it arrived safely.
Step 1: build the invoice and save it as a PDF. A PDF cannot be edited by accident, opens on any device, and uploads cleanly into accounting software. Name the file clearly, for example INV-1042-YourBusiness.pdf, so the client can find it again. You can build and download one in minutes with LancerBill’s invoice generator, which needs no signup.
Step 2: check the invoice before you attach it. Confirm the invoice number is unique, the client’s legal name is spelled right, the total adds up, the payment details are current, and the due date matches the terms you agreed. A wrong sort code or account number is the single most common cause of a failed first payment.
Step 3: write the subject line. Use this formula: Invoice [number] from [your business], due [date]. It survives forwarding, it is searchable in an inbox months later, and it tells the reader the deadline before they even open the message.
Step 4: keep the body to three or four sentences. Thank the client for the work, state that the invoice is attached, give the total and the due date, and say how to pay or where the payment details sit. Close by asking them to confirm receipt. That confirmation is your proof of delivery if there is a dispute later.
Step 5: send it promptly and file your copy. Send the invoice the day the work is delivered, or on the agreed billing date for retainers. Late invoicing signals that you are relaxed about being paid. Save the sent email, because the thread becomes your timeline if you ever need to chase.
Tip: Put the amount and due date in the body even though they are also on the PDF. Many clients pay from the email itself, and their accounts team often keys the payment run from the figures in front of them.
Copy-paste templates for the first invoice email
Each template below follows the same pattern: subject line, three short body sentences, sign-off. Swap the bracketed fields and send. Keep your own wording if you prefer, but do not drop the invoice number, total, due date, or payment method. Those four items do the work.
Template 1: the standard first invoice
Subject: Invoice INV-1042 from Maya Hart Design, due 2 November 2026
Hi Sam,
Thanks for the project. Invoice INV-1042 is attached for the brand refresh work completed this week. The total is £1,183.20, due on 2 November 2026, and my bank details are on the invoice.
Please confirm you have received it, and shout if anything looks off.
Best wishes,
Maya
Template 2: a deposit or upfront invoice
Subject: Deposit invoice INV-1043 from Maya Hart Design, due 23 October 2026
Hi Sam,
As agreed, invoice INV-1043 is attached for the 50 percent deposit on the website project. The deposit is £900, due on 23 October 2026, and I will book the start date once it lands.
The balance invoice will follow on delivery. Please confirm receipt.
Best wishes,
Maya
Template 3: a retainer or monthly invoice
Subject: Invoice INV-1044 from Maya Hart Design for October, due 31 October 2026
Hi Sam,
Invoice INV-1044 is attached for October’s support retainer. The total is £600, due on 31 October 2026, and the bank details are unchanged from last month.
Please confirm receipt, and let me know if your accounts team needs anything else from me.
Best wishes,
Maya
Template 4: sending an invoice with a quote attached for the next job
Subject: Invoice INV-1045 and quote for phase two, from Maya Hart Design
Hi Sam,
Two attachments with this email. Invoice INV-1045 covers the finished work, £450 due on 6 November 2026. The second file is a quote for phase two, valid for 30 days, with the price held at the figure we discussed.
Please confirm the invoice arrived safely.
Best wishes,
Maya
For that second attachment, build the quote with the same line items you plan to invoice later. A free quote generator keeps the two documents consistent, which removes the “that is not what you quoted” conversation entirely.
A worked example with the numbers checked
Assumptions: Maya is a UK freelance designer, VAT registered, sending one invoice on Monday 19 October 2026 on Net 14 terms. Her invoice INV-1042 covers:
| Line item | Calculation | Amount |
|---|---|---|
| Brand refresh, 2 days | 2 x £400 per day | £800.00 |
| Extra revisions, 3 hours | 3 x £50 per hour | £150.00 |
| Stock images bought for the job | At cost | £36.00 |
| Subtotal before VAT | 800 + 150 + 36 | £986.00 |
| VAT at 20 percent | 986 x 0.20 | £197.20 |
| Total due | 986 + 197.20 | £1,183.20 |
The due date maths: 19 October plus 14 days is 2 November 2026. Her email subject line, template 1 above, carries the invoice number, her business name, and that date. The body repeats the £1,183.20 total. The client needs nothing else to pay.
Now the follow-up dates, worked out before she sends anything. A friendly check three working days before the due date lands on 28 October. The due date itself is 2 November. A firmer reminder seven days after lands on 9 November. Putting all three dates in her diary at the moment she sends the invoice takes one minute and means the chasing never depends on memory.
If the invoice were paid 14 days late and she chose to claim UK statutory interest, the illustration, using an assumed 12 percent annual rate (the statutory 8 percent plus an assumed 4 percent Bank of England base rate), would be: £1,183.20 x 0.12 = £141.98 a year; £141.98 / 365 = £0.39 a day; £0.39 x 14 days = £5.45. On top of that, GOV.UK’s late commercial payments guidance sets fixed compensation of £70 for a debt between £1,000 and £9,999.99, so the total addition would be £75.45. Check the live base rate before claiming, and run your own figures through a late payment fee calculator rather than estimating.
When should you chase an unpaid invoice by email?
Send a friendly check three to five days before the due date, a short reminder on the due date itself, and a firmer note seven days after it passes. Reattach the invoice every time, restate the amount and original due date, and keep each message polite, specific and easy for the client to act on.
Most late payment is admin, not malice. Your invoice is sitting in the wrong inbox, waiting for a purchase order, or behind a monthly payment run. Your reminder sequence should assume that until the evidence says otherwise. Escalate the clarity, not the anger.
| When | Message | Tone |
|---|---|---|
| 3 to 5 days before due date | Confirm the invoice arrived and ask if anything is needed from you | Friendly, helpful |
| On the due date | Short note that payment is due today, invoice reattached | Neutral, brief |
| 7 days overdue | State the days overdue, the amount, and ask for a payment date | Firm, specific |
| 14 to 30 days overdue | Final reminder naming late payment interest and your next step | Formal |
Reminder template: seven days overdue
Subject: Reminder: invoice INV-1042 for £1,183.20, due 2 November 2026
Hi Sam,
Just flagging that invoice INV-1042 for £1,183.20 was due on 2 November and I have not seen payment yet. I have reattached it in case the original went astray.
Could you confirm when it will be paid? If it has already gone through, ignore this and thank you.
Best wishes,
Maya
If reminders stop working, stop emailing and change approach. Our guide on what to do when a client does not pay walks through the escalation steps, from pausing work to formal recovery. And if the client pays part of the bill or pays by a different route, send a receipt for the amount received. A receipt generator keeps that record as tidy as the invoice.
Watch out: Never send a reminder without reattaching the invoice. “Please pay the attached” forces the client to dig through old threads. Every extra minute of hunting is another reason for your invoice to slip to the next payment run.
Which template should you use?
Use this quick decision framework instead of writing from scratch each time. The situation decides the template, the template decides the tone, and the tone protects the relationship while the facts, the amount, the due date and the invoice number, do the chasing for you in every single message you send.
| Situation | Use | Must include |
|---|---|---|
| Work finished, first billing | Template 1 | Number, total, due date, payment details |
| Project agreed, not started | Template 2 | Deposit percent, amount, what payment triggers |
| Same client, every month | Template 3 | Month covered, total, note if details changed |
| Repeat work likely | Template 4 | Invoice plus a dated, time-limited quote |
| Payment late | Reminder template | Days overdue, reattached invoice, request for a date |
Notice what none of these templates contain: an apology for invoicing. You did the work, the price was agreed, and asking for payment is a normal part of the job. Templates also remove the temptation to over-explain. Three sentences that a stranger could act on will outperform a long, warm email that buries the due date in paragraph four.
Finally, check your terms language matches the email. If your invoice says Net 30 but your email says “due next week”, you have created a dispute. Our explainer on invoice payment terms like Net 30 and due on receipt shows how to phrase terms so the date in your subject line is the date the client agreed to.
Key takeaways
- Subject line formula: invoice number, your business name, due date. Nothing vaguer.
- The email body repeats the total, the due date and how to pay, even though the PDF says it too.
- Always attach a PDF, named with the invoice number, and ask for confirmation of receipt.
- Send to the person who approves payment, and quote a purchase order number if one was issued.
- Set three reminder dates in your diary the moment you send: before due, on the day, seven days after.
- Reattach the invoice with every reminder and escalate clarity, not anger.
Frequently asked questions
Should I put the invoice in the email body or as an attachment?
Attach it as a PDF, and repeat the key facts in the body. A PDF is a fixed record that accounting software can import and the client cannot edit by accident. The body carries the invoice number, total and due date so the email alone is enough to trigger payment.
What is the best subject line for an invoice email?
Use “Invoice [number] from [your business], due [date]”. It names the document, the sender and the deadline, it stays meaningful when forwarded to an accounts team, and it is easy to find later with an inbox search for the invoice number.
When is the best time to send an invoice?
Send it the day you deliver the work, or on the agreed monthly billing date for retainers. Invoicing promptly starts the payment clock sooner and signals that you track your money. For business clients, sending early in the working week also helps you catch their weekly payment run.
Do I need to ask the client to confirm receipt?
Yes. A one-line confirmation proves the invoice reached the right person on a known date. That proof matters if the client later claims the invoice never arrived, and it surfaces problems early, such as a missing purchase order number, while there is still time to fix them before the due date.
How do I send an invoice to a big company with an accounts department?
Ask your contact, before you start work, for the accounts payable email address and whether a purchase order number is required. Send the invoice to accounts, copy your contact, and quote the purchase order number in the subject line, the body and on the invoice itself.
Can I charge interest if an emailed invoice is paid late?
In the UK, business-to-business invoices generally carry a statutory right to interest at 8 percent above the Bank of England base rate, plus fixed compensation of £40, £70 or £100 depending on the debt, unless your contract sets its own rate. GOV.UK publishes the rules. Check the current base rate and your contract before adding anything.
Invoice and late payment rules last reviewed: October 2026.
This guide is for general information only and is not financial, tax or legal advice.