A direct debit clause in your terms gives you the right to ask for a mandate, but you can't collect anything until each client has signed one. Getting everyone across is an onboarding and follow-up job: send the mandate with the contract, chase it until it's signed, explain that one mandate covers amounts that change, and move long-standing bank-transfer clients at renewal. For the few who still refuse, send a payment link they can pay by bank or card, so you aren't waiting on a transfer.
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The short version
- A contract clause saying fees are payable by direct debit collects nothing until each client has actually signed a mandate.
- Send the mandate link with the contract or welcome email, then chase it around day three and day seven and put it on every invoice until it's signed.
- Move long-standing bank-transfer clients at a renewal, price review or change in services, starting with late payers and those whose invoices vary.
- One mandate collects changing monthly amounts and one-off charges, with advance notice of 10 working days under the Guarantee unless another period is agreed.
- For clients who won't sign, send a pay by bank link, and keep bank transfer only for those who will use nothing else.
How to get the mandate signed at the start
"Fees are payable monthly by direct debit" is in most MSP contracts. The gap opens straight after signing: the mandate isn't collected, the first invoice goes out as a bank transfer request, and the client never has a reason to change.
The easiest moment is the day a client says yes. Send the mandate link with the contract or welcome email, not with the first invoice, so it reads as part of signing up. Say in one line what it does: "This sets up the monthly direct debit in your terms, and you'll get notice of each amount before it's collected." Ask who authorises payments at the client, because at larger firms it's often a finance contact you haven't met. Then put mandate status on the onboarding checklist next to the RMM deployment, and leave a few working days before the first collection, because a new mandate has to be lodged with the client's bank first.
Unsigned mandates need chasing, because most clients mean to sign and don't get round to it. A reminder around day three, a call or message to the person who signs around day seven, and the mandate link on every invoice until it's done will get most of them over the line. Adfin handles this part for you. It chases unsigned mandates, and if one still isn't in place when an invoice falls due, it offers the client another way to pay so you're paid that month anyway. Its AI agents can pick the timing and channel for each reminder, email, SMS or WhatsApp, within rules you approve.
Track one number each month: the share of recurring clients with an active mandate. Clients can cancel through their bank without telling you, so treat a cancellation notice like an unsigned mandate.
How to move clients who've paid by bank transfer for years
Clients who've paid by transfer for years are harder, and plenty of them pay on time, so it's tempting to leave them alone. Before you contact anyone, sort them. Start with the clients who pay late and the ones whose invoice changes every month, where the case is easiest to make and a manual transfer is most likely to be late or for the wrong amount. Leave the rest for a natural change point, such as a contract renewal, a price review or a change in services, and send the mandate with the new paperwork.
Frame it around their process as well as yours: "We're moving all clients onto direct debit so invoices are collected on the due date without anyone making a transfer. You'll still get every invoice, with notice of each amount before it's collected, and you can cancel through your bank at any time." Send the link in the same message.
Decide who asks. A request from the account manager who speaks to the client every week feels like part of the relationship, while the same request from finance can feel like collections. And give it more than one go, because a phone call to the right person often gets further than a third email.
How one mandate covers amounts that change
The objection you'll hear most is "our invoice changes every month". A mandate doesn't fix the amount. It can differ from one collection to the next, including one-off charges, and the client doesn't sign again. Instead they get advance notice of each amount: the Direct Debit Guarantee sets this at 10 working days unless you've agreed a different period, and many providers agree a shorter one in their terms. Make sure your contract says the same as your provider.
Take a client on 30 users at £40, collected at £1,200 in April. In May three starters take it to £1,320, and a laptop order goes as a separate £850 collection. In June two leavers bring it to £1,240. The client signed once, in April, and saw each amount before it was taken. Adfin's direct debit collects whatever each invoice says under that one mandate, so seat changes and hardware orders don't send you back for a signature.
A finance contact who likes to approve each payment usually finds this reassuring once it's explained: they still see every invoice, and the notice period gives them time to query one before the money moves. A short paragraph in your welcome pack covers it before it becomes a reason to say no.
What to do when a client won't sign
Some won't, often because of a company policy against supplier direct debits. Give these clients a method you still start, where the money arrives at the right amount with the right reference. A pay by bank link is the usual compromise: the client taps it, sees the invoice and approves the payment in their banking app. A card payment is quick for them but costs you more; you can pass the fee on for business cards, capped at what it costs you to accept them, but not for personal cards. Keep bank transfer only for clients who will use nothing else, and give each a clear reference.
Common questions
Can I refuse to work with a client who won't sign a mandate? That's a commercial decision that depends on your contract. Many MSPs offer a pay by bank link first, which keeps the relationship and still gets them paid on time.
Does a client need to sign a new mandate when the amount changes? No. One mandate covers different amounts and one-off charges, as long as the client gets advance notice of each collection.
Can a mandate be tied to the length of the contract? No. A mandate is open-ended and the client can cancel it through their bank at any time. The contract carries the term.
What should I say to a client whose finance team approves every payment? That they'll still get every invoice and notice of each amount before it's collected, so there's time to query it. If their policy bans supplier direct debits, offer a pay by bank link.
When is the best time to move an existing client onto direct debit? At a renewal, price review or change in services, when you're already sending new paperwork. Start with late payers and clients whose invoices vary.
What happens if a client cancels their mandate without telling me? Your provider should notify you. Contact the client, send a payment link for anything due, and ask them to set up a new mandate.
Sources
- Pay.UK (Direct Debit) - The Direct Debit Guarantee (accurate as of September 2026) https://www.directdebit.co.uk/direct-debit-explained/direct-debit-guarantee/
- Department for Business, Energy and Industrial Strategy - The Consumer Rights (Payment Surcharges) Regulations 2012 guidance (accurate as of September 2026) https://assets.publishing.service.gov.uk/media/5b2d09bae5274a55bb5790cb/payment-surcharges-guidance-update.pdf
- Adfin - Next-generation direct debit (accurate as of September 2026) https://www.adfin.com/direct-debit-payments
- Adfin - Credit control (accurate as of September 2026) https://www.adfin.com/credit-control
