Big clients who only pay by bank transfer pay on their own payment runs, so getting paid on time comes down to being set up correctly as a supplier, getting each invoice approved before the run you're aiming for, and chasing their accounts payable team rather than the person who hired you. Give each client bank details that identify them, so their payment matches the right invoices when it lands.
In this article
The short version
- Big clients pay through accounts payable on fixed payment runs, so they rarely sign direct debit mandates.
- Finish supplier set-up and quote the PO and exact legal entity on every invoice.
- Ask for payment run dates and approval cut-offs, and time invoices to land before them.
- Chase accounts payable with the invoice, PO and amount, and send statements.
- Under the Procurement Act 2023, most public contracts require undisputed invoices to be paid within 30 days.
Why big clients only pay by bank transfer
Large companies, councils, NHS bodies and universities tend to pay every supplier the same way. Invoices go into an accounts payable system, get checked against a purchase order, get approved, and then wait for the next payment run, when a batch of bank transfers goes out together. Some run weekly, many fortnightly or monthly.
That process is why they won't sign your direct debit mandate. Letting a supplier take money from their account would bypass the approval step their controls are built around, so the answer is usually no, however small the amount. You're unlikely to change that policy. What you can change is how cleanly your invoice moves through it.
It helps to know their published standards. Large companies report how quickly they pay suppliers, and many have signed the Fair Payment Code, run by the Small Business Commissioner. A gold award, for example, means paying at least 95% of all invoices within 30 days. Public bodies have a firmer rule: under the Procurement Act 2023, most public contracts carry a term that undisputed, valid invoices are paid within 30 days of being received, and the authority has to tell you without undue delay if it disputes an invoice or considers it invalid. Contracts awarded by schools are an exception.
Get each invoice onto the right payment run
Most late payment from big clients happens before anyone has decided to pay late. The invoice is stuck somewhere: wrong entity, missing PO, sent to the wrong inbox. A few habits keep it moving:
- Complete supplier set-up in full before you start the work, including bank details, VAT number and any insurance documents they ask for.
- Invoice the exact legal entity on the purchase order, which may not be the brand you dealt with.
- Quote the PO number, and any line or goods received reference, on every invoice.
- Send it exactly where they ask: a portal, a named inbox, or both.
- Ask accounts payable when their payment runs are and the cut-off for approval before each one.
That last question changes how you invoice. If a client pays on the last Thursday of the month and needs invoices approved a week before, an invoice sent two days after the cut-off waits nearly a month longer than one sent two days before it. Where your contract allows, time your invoices to land ahead of the cut-off, and check that the payment terms run from the invoice date, not the date someone gets round to approving it.
Give each big client their own bank details for paying you. Their remittance often carries their own payment reference, not your invoice number, and a bank transfer into a shared account can take a while to work out. Adfin gives each customer unique bank details in your business's name, which you enter once on their supplier form. When their payment run sends the money, it's matched by reference, then amount, then to the most overdue invoice, and marks the invoices paid in Xero or QuickBooks.
Chase accounts payable, not the buyer
The person who commissioned the work usually can't see where your invoice is or speed it up. Accounts payable can. Set them up as a contact for that client, and when you chase, put the invoice number, PO number and amount in the first line, then ask two plain questions: is it approved, and which payment run is it on.
Statements tend to work better than single reminders with large clients, because one email listing every open invoice gets reconciled against their ledger in one go. With Adfin, you can send statements with a single link to pay everything outstanding, and Adfin's collection agents can send reminders to the contacts you choose on a schedule you approve.
When an invoice is approved but still unpaid after the run it was due on, it's reasonable to get firmer. On Adfin's Enhanced credit control, escalations send a firmer notice from a connected mailbox you choose for each stage, such as a director's, and can end with handing the invoice back to you or to Garfield.Law, Adfin's partner law firm. On a business invoice you're also entitled to statutory interest, at 8% above the Bank of England base rate, plus fixed compensation. Many suppliers keep that in reserve for clients who pay late repeatedly.
When to ask for direct debit anyway
Some clients will sign a mandate if you ask early, especially mid-sized firms that don't run formal payment runs, or any client paying you a fixed amount every month. Raise it at onboarding, when payment terms are already being discussed, and put it in your terms. If a client then refuses, you've lost nothing, and bank transfer with unique details is a reliable fallback.
For one-off large invoices, a mandate can feel like a bigger ask than the payment itself. Some providers also set a default limit on a single direct debit collection, which you'd need to ask them to raise or work around by splitting the bill. It's often simpler to accept that the client will pay by transfer and concentrate on getting the invoice approved before the run.
Related guides
- How do I get paid by big companies that use supplier portals?
- How to get every client onto direct debit, even when it's already in your T&Cs
- Can you collect a £30,000 invoice by direct debit?
- How much interest can you charge on late payments in the UK?
- Credit control: a complete guide
Common questions
Why won't large companies pay by direct debit? Their accounts payable process approves each invoice before it's paid, and a direct debit would let a supplier take money without that step. Most apply this to every supplier.
How do I find out when a big client pays? Ask accounts payable for their payment run dates and the approval cut-off before each run. Large companies also publish how quickly they pay suppliers.
What is the Fair Payment Code? It's a scheme run by the Small Business Commissioner that awards businesses gold, silver or bronze for how quickly they pay suppliers. Gold means paying at least 95% of all invoices within 30 days.
How long can a public body take to pay my invoice? Under the Procurement Act 2023, most public contracts require undisputed, valid invoices to be paid within 30 days of receipt. Contracts awarded by schools are an exception.
Who should I chase when a big client pays late? Their accounts payable team, with the invoice number, PO number and amount up front. The person you worked with can help get an invoice approved, but rarely controls payment.
Can I charge a big client interest for paying late? On a business invoice, yes. You can claim statutory interest at 8% above the Bank of England base rate, plus fixed compensation, unless your contract sets a different remedy.
Sources
- Small Business Commissioner - The new Fair Payment Code (accurate as of November 2026) https://www.smallbusinesscommissioner.gov.uk/news/the-new-fair-payment-code/
- legislation.gov.uk - Procurement Act 2023, section 68 (accurate as of November 2026) https://www.legislation.gov.uk/ukpga/2023/54/section/68
- GOV.UK - Check when large businesses pay their suppliers (accurate as of November 2026) https://www.gov.uk/check-when-businesses-pay-invoices
- GOV.UK - Late commercial payments: charging interest on commercial debt (accurate as of November 2026) https://www.gov.uk/late-commercial-payments-interest-debt-recovery/charging-interest-commercial-debt
- Adfin Help Centre - An introduction to Adfin bank transfers (accurate as of November 2026) https://support.adfin.com/en/articles/12600901-an-introduction-to-adfin-bank-transfers
