Agree the terms before you start, send the invoice the day the work finishes, address it to someone who can approve it, and put the amount, the due date and any purchase order number where they can't be missed. Then give your customer a way to pay straight from the invoice, because the fewer steps paying takes, the sooner it tends to happen.
In this article
The short version
- Agree payment terms and find out who approves invoices before you start the work.
- Send the invoice the day the work finishes, with the due date written as a date.
- Address it to a named person and quote their purchase order number.
- Add a payment link so your customer can pay in a few taps.
- In Adfin's data, 42.9% of customer-initiated payments arrived within 24 hours of the request.
Before you send anything
A correct invoice is the starting point: a unique number, both parties' details, a description, the supply date, the invoice date and the amount owed. Missing details give your customer a reason to query it, and payment usually waits while a query gets answered. Two more things are worth sorting before the first invoice goes out, because you can't fix either at the moment of sending.
Agree your payment terms when you agree the work. Terms that first appear on the invoice can be questioned at exactly the wrong moment, while terms in a signed quote or engagement letter are simply what was agreed.
Find out who approves invoices and what they need. On larger jobs, the person you deal with often can't authorise payment, and many finance teams won't pay without a purchase order number. Ask once, at the start, and keep the answer with the customer's details.
How to write and send the invoice
- Send it the day the work finishes. If you never agreed terms, the 30 days a business customer has by law doesn't start until they know the amount, so a week's delay at your end adds a week at theirs.
- Write the due date as a date. "Due 14 November 2026" needs no working out, while "30 days" invites a conversation about when the 30 days started.
- Put the amount and the due date in the email subject line, so they survive being skimmed on a phone.
- Address it to a named person. A shared accounts inbox tends to be worked through in order, so if your customer insists on it, copy in the person who approved the work.
- Quote the purchase order number, project code or reference your customer gave you.
- Keep the email short: one amount, one date and one thing to do. A long explanation of the work above the figure tends to get the invoice read later.
- Give them a way to pay from the invoice itself. A payment link lets your customer pay from their phone with the reference already filled in, instead of setting you up as a new payee in their banking app.
- Offer more than one way to pay. Your customer is more likely to pay promptly with a method they already use, whether that's a card, Apple Pay, Google Pay or a bank payment.
What the payment data shows
Adfin's own payment data shows how much the first couple of days matter. Of the payments where the customer chose when to pay, 42.9% arrived within 24 hours of the payment request, and the median was 53 hours. When an invoice reaches someone who can pay it, payment often follows within a day or two, and an invoice that sits in the wrong inbox misses that window.
These figures describe what happened rather than prove what causes it, but they point the same way as the steps above. The sooner the right person sees your invoice, and the fewer steps there are between seeing it and paying it, the sooner the money tends to arrive.
How to plan the follow-up when you send it
Decide your follow-up when you send the invoice, not when it's already overdue. A reasonable pattern is a short note a few days before the due date checking the invoice reached the right person, a reminder on the day, and follow-ups at set intervals after that, each with the payment link.
The note before the due date is there to catch problems early. If your invoice is sitting with the wrong person or waiting for a purchase order, you find out while there's still time to fix it.
For business customers, it also helps to say on the invoice that statutory interest and compensation apply to late payment. The right exists whether or not your contract mentions it, and saying so sets the expectation without sounding like a threat.
If you'd rather not run this by hand, Adfin can put a payment link on every invoice and send it by email, SMS or WhatsApp, so your customer can pay by card, Apple Pay, Google Pay or pay by bank. Its AI Customer Agents then follow up on the schedule and channels you choose, from your own email domain, so reminders go out on time without anyone having to remember.
Common questions
What makes an invoice get paid faster? Fewer steps between seeing it and paying it: a named recipient, a clear due date, the reference your customer needs and a payment link they can use straight away.
Should I put payment terms on the invoice? Yes, as a date. If you agreed nothing with a business customer, the law gives them 30 days from the later of the work being done and them being told the amount.
Is it better to send an invoice as an attachment or a link? A link, ideally alongside the invoice itself. A link can be paid from a phone in a few taps, while an attachment with bank details needs a separate bank transfer.
Does it matter when I send the invoice? Yes. Send it as soon as the work is done, because terms usually run from when your customer gets the invoice, so any delay at your end comes out of your cash.
When should I start following up? Before the due date. A short check that the invoice reached the right person gives you time to fix any problem before it's late.
Should my invoice mention late payment interest? For business customers it helps. Statutory interest applies whether or not you mention it, and stating it sets the expectation early.
Sources
- GOV.UK - Invoicing and taking payment from customers: invoices, what they must include (accurate as of October 2026) https://www.gov.uk/invoicing-and-taking-payment-from-customers/invoices-what-they-must-include
- GOV.UK - Late commercial payments: charging interest on commercial debt (accurate as of October 2026) https://www.gov.uk/late-commercial-payments-interest-debt-recovery/charging-interest-commercial-debt
- legislation.gov.uk - Late Payment of Commercial Debts (Interest) Act 1998, section 4 (accurate as of October 2026) https://www.legislation.gov.uk/ukpga/1998/20/section/4
- Adfin - Credit control (accurate as of October 2026) https://www.adfin.com/credit-control
