Getting paid

The Invoice Email: What to Write and When to Follow Up

A great invoice attached to a bad email gets paid late. The email is what determines whether the invoice reaches the person who can approve it, whether they understand what it is without opening anything, and whether it resurfaces when it needs to. It is thirty seconds of writing that materially changes when the money arrives, and most people spend those thirty seconds writing "Please find attached."

By Arshad Hossain · Published 16 August 2026

The short version

Put the amount and due date in the email body, not only in the attachment.
Send to whoever approves payment, and copy your day-to-day contact.
Attach a PDF named with your business and the invoice number.
Follow up on a schedule, not on how annoyed you feel.

Send it to the right person

The most common reason an invoice sits unpaid is not reluctance. It is that it arrived in the inbox of someone with no authority to pay it, who fully intended to forward it.

Your day-to-day contact is usually not the approver. In anything larger than a very small business, invoices go to accounts payable, a finance mailbox, or a manager with budget authority. Ask during onboarding: who should invoices go to, is there a shared mailbox, is a purchase order number needed, and when is the payment run.

Then send to the approver and copy your contact. The copy matters — your contact is the person who cares whether you are happy, and they are the one who will chase internally when you follow up.

Where a client uses a portal rather than email, use the portal. Invoices emailed to a client with an AP system frequently never get entered at all.

The subject line does real work

Subject lines get scanned in a list of forty. Yours needs to be identifiable and searchable months later.

Include your business name, the word Invoice, the number, and the amount. "Invoice INV-0042 from Ashgrove Design — £2,400 due 14 September" tells the reader everything before they open anything, and it is findable by amount, number or name when someone searches for it later.

Avoid "Invoice attached" and "Payment request", which are indistinguishable from every other invoice in the inbox and from a fair amount of spam.

For follow-ups, keep the same thread rather than starting a new one. The history is the point — it shows the original send date without you having to assert it.

Invoice INV-0042 from [Your Business] — £2,400 due 14 September
Invoice INV-0042 — [Client] project, £2,400, due 14 September
Reminder: Invoice INV-0042 — £2,400, due tomorrow
Overdue: Invoice INV-0042 — £2,400, 14 days past due

What goes in the body

Repeat the essentials in the email body. Not everyone opens the attachment before deciding what to do with the message, and some AP systems display only the body text.

Four things: what the invoice is for, the amount, the due date, and how to pay. Three sentences. Then a line thanking them, and stop.

Do not apologize for invoicing. "Sorry to chase" and "I hope you don't mind" undermine a routine commercial request and, in practice, make it easier to deprioritise. You did the work; the invoice is the expected next step.

Do not put payment terms up for negotiation by asking "let me know if that works". State the due date as a fact. If a client needs different terms they will say so, and that is a conversation worth having explicitly rather than inviting by default.

A follow-up sequence that works

Follow up on a schedule, not on emotion. A schedule means it happens consistently, at the right intervals, without you having to decide each time whether you are being pushy.

Three days before the due date, send a short courtesy note. This is the highest-value message in the sequence and almost nobody sends it. It catches invoices that were never entered, arrives while the client feels helpful rather than defensive, and is genuinely appreciated.

On the due date, if unpaid, reply in-thread noting it is due today and asking for a payment date.

Seven days after, reply again asking for a specific date and whether anything is blocking approval. Asking what is blocking it often surfaces a missing PO number or a wrong address in seconds.

Fourteen days after, change register: a firm, plain message stating the amount, the days overdue, and a deadline. Copy your contact if you have not been.

Beyond thirty days you are into escalation, covered in how to chase an unpaid invoice.

When	Tone	Ask for
3 days before due	Courtesy	Confirmation it is scheduled
Due date	Neutral	A payment date
+7 days	Direct	A date, and what is blocking it
+14 days	Firm	Payment by a stated deadline
+30 days	Formal	Payment, with next steps stated

Invoice email questions, answered

What should I write when sending an invoice by email?

Three sentences: what the invoice covers, the amount and due date, and how to pay. Attach the PDF, thank them, and stop. Repeat the amount and date in the body, since not everyone opens the attachment before deciding what to do.

What is a good subject line for an invoice email?

Include your business name, the word Invoice, the number and the amount — "Invoice INV-0042 from Ashgrove Design — £2,400 due 14 September". It is identifiable in a crowded inbox and findable by any of those terms months later.

Who should I send my invoice to?

The person or mailbox that approves payment, copying your day-to-day contact. Ask at onboarding whether there is an accounts payable address, a portal, or a purchase order requirement — invoices sent only to your contact routinely stall in forwarding.

Should I send my invoice as a PDF or in the email body?

Attach a PDF and summarize it in the body. The PDF is the record and is what AP systems expect; the body summary means the essentials are visible without opening anything, which matters more than people assume.

What should I name my invoice file?

Something that survives being downloaded into a folder of thirty others: Invoice-INV-0042-YourBusiness.pdf. A file called invoice.pdf or document.pdf gets lost, and lost invoices get paid late through nobody's ill will.

When should I follow up on an unpaid invoice?

Three days before the due date as a courtesy, on the due date, then at seven and fourteen days overdue. Following up on a schedule rather than on how annoyed you feel means it happens consistently and stays professional.

Should I apologize for chasing an invoice?

No. Requesting payment for completed work is a routine commercial act, not an imposition. Apologetic framing signals the request is negotiable and makes it easier to deprioritise. Be polite and plain rather than sorry.

Is it rude to send a reminder before the invoice is due?

Not at all, and it is the most effective message in the sequence. A short note a few days ahead catches invoices that were never entered into the client's system, and it arrives while everyone still feels cooperative.

Should I email or use the client's invoicing portal?

Use the portal where one exists. Clients with AP systems frequently never enter emailed invoices at all, and portal submissions are timestamped, which gives you a record of when the clock actually started.

How do I write a final payment reminder?

Plainly and without hostility: the invoice number, the amount, how many days overdue, what you want, and by when. Drop the softening language, keep the professionalism, and state clearly what happens if the deadline passes.

Should I copy my main contact on chasing emails?

Yes, from the second follow-up onward. Your contact is the person who cares about the relationship and is best placed to chase internally. Escalating above them without telling them first is what damages relationships, not the copy itself.

How many times should I follow up before escalating?

Three or four spaced messages over roughly a month, then move to a formal written demand. Sending the same soft reminder weekly for three months trains the client that nothing follows from ignoring you.

Frequently Asked Questions

Should I send invoices at a particular time of day?

Mid-morning on a Tuesday to Thursday tends to land better than late Friday, when it will be reviewed on Monday alongside everything else. It is a marginal effect, well behind sending to the right person and invoicing promptly.

Should I use read receipts on invoice emails?

Generally not. They read as distrustful, are widely ignored or blocked, and prove little — a read receipt does not show the invoice reached the approver. If you need proof of delivery, a client portal timestamp is far better evidence.

What if the client says they never received the invoice?

Resend it immediately with the original number and date unchanged, and copy a second contact. Do not reissue with a new date, which restarts the payment clock in their favour. Then ask whether there is a portal or AP address you should be using instead.

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