Your mandates live at your customers' banks, not with your provider, so a switch changes who collects under them rather than the mandates themselves. In a Bacs bulk change the instructions are transferred to your new provider and your customers sign nothing; on the other route, each customer signs a new mandate. Either way, the days around the change date need planning.
In this article
The short version
- Mandates sit at your customers' banks; a switch changes who collects under them.
- In a Bacs bulk change customers sign nothing; otherwise each signs a new mandate.
- Bacs expects about four to six weeks, mostly waiting for the sponsoring banks.
- Plan the short gap around the change date so nobody is missed or charged twice.
- Afterwards, compare active mandates with your old records and follow up any gaps.
The two routes a switch can take
When you collect through a direct debit provider, your collections run under its Service User Number (SUN), the six-digit identifier the Bacs scheme gives every organisation that collects by direct debit. Each customer's mandate is an instruction at their bank allowing collections under that number. Changing provider changes the number, so every instruction has to be updated or replaced.
There are two ways to do that:
- A Bacs bulk change: your old and new providers, and their sponsoring banks, agree a change date and the instructions are moved across in one go. Your customers get written notice and don't sign anything.
- New mandates: each customer signs a fresh mandate with your new provider. There's no bank approval to wait for, but you're relying on every customer to act.
The route you're offered depends on your new provider. With Adfin, 10 or more mandates move on the bulk change and fewer than 10 move by customers signing a new mandate online, which avoids a wait of several weeks for a handful of customers.
What a bulk change does behind the scenes
Bacs publishes three ways of running a bulk change, and your customers do nothing in any of them:
- Transfer of the SUN: when every mandate is moving and the number itself can be handed over, the instructions at your customers' banks don't need to change at all.
- Transfer of all instructions: the old provider cancels each instruction at the customer's bank and the new provider creates a matching one under its own number, electronically, through AUDDIS (the Bacs service for lodging and cancelling mandates without paper).
- Transfer of some instructions: the same process, for part of your customer list. Agree exactly which customers are included before anything starts.
So in the second and third options your mandates are, strictly, cancelled and re-created. Your customers don't see that happen and aren't asked for anything, but it's the reason a few mandates can fail to arrive, which the last section covers.
Responsibility for refunds moves with the instructions. Under the Bacs bulk change deed, your old provider stays responsible for refund claims on collections made before the transfer date, and your new provider takes them on for collections after it. The Direct Debit Guarantee doesn't change for your customers: they still get advance notice of changes, a full refund if a payment is taken in error, and the right to cancel at any time through their bank.
Bacs expects the basic switching procedure to take about four to six weeks, most of it waiting for the two sponsoring banks to approve, and Adfin allows for that by booking change dates at least five weeks ahead.
Collections either side of the change date
Providers build a short gap around the change date, when the old provider has stopped submitting collections and the new one hasn't started. Your old provider is likely to ask you to stop creating collections several days before the change date, and the new provider starts collecting a few working days after it, once the moved mandates are active. On Adfin, migrated mandates become active three working days after the change date.
No invoice has to go uncollected, but some collection dates will move for one cycle. Before the gap starts, list every customer whose collection falls in the weeks around the change date and decide which side takes their next payment: an early final collection with the old provider, or a first collection with the new one after the gap. Give advance notice of any new date, and make sure only one collection goes out for each invoice.
Your schedules don't move with the mandates. A mandate is permission to collect and carries no amounts, dates or invoices, so recurring schedules and instalment plans have to be set up again on the new side before the first collection date. Check each one against what the customer was told.
Mandates that don't make it across
Some instructions don't transfer cleanly, usually because the details behind them were wrong or out of date: an account that has since closed, a customer who moved bank, a missing account holder name. When a new instruction can't be created, the customer's bank rejects it, and the rejection goes to your new provider rather than to you.
So once the change date has passed, compare the list of mandates your new provider shows as active with your old provider's records, and follow up every gap. For each missing customer, the fix is a new mandate, signed online. Until it's signed, they still need a way to pay, or their next invoice simply goes unpaid.
You can reduce the gaps before you start: check every customer record has the account holder's name, email and postal address, and remove duplicates and customers who no longer pay you.
Adfin chases customers who haven't signed a new mandate and offers them another way to pay in the meantime, such as a card or a pay by bank link, so no invoice is left without a route to payment. Its collection agents can carry on chasing anything that slips during the switch, within rules you set and approve.
Common questions
Do my customers have to sign a new mandate when I switch provider? Not if your mandates move through a Bacs bulk change. If your new provider moves them as new mandates instead, each customer signs one.
Are my mandates cancelled during a bulk change? Under some bulk change options the old instruction is cancelled and a new one created electronically at the customer's bank. Your customers don't have to do anything either way.
How long does it take to switch direct debit provider? Bacs expects about four to six weeks, mostly waiting for the sponsoring banks. Adfin books the change date at least five weeks after you ask.
Will my collections stop during the switch? There's a short gap of several days around the change date. Plan which side takes each customer's next payment so nobody is missed or charged twice.
Who handles refund claims after the switch? Your old provider for collections made before the transfer date, and your new provider for collections after it, under the Bacs bulk change deed.
What happens if a mandate doesn't transfer? That customer needs to sign a new mandate. Compare the list of active mandates with your old records after the change date and follow up every gap.
Sources
- Bacs - The little Bacs guide to switching facilities management provider (accurate as of October 2026) https://www.bacs.co.uk/media/xglbtzor/little_bacs_guide_to_switching_fm_providers.pdf
- Bacs - Direct Debit Scheme bulk change deed (accurate as of October 2026) https://www.bacs.co.uk/media/bdpfhdc4/dd_bulk_change_deed_b.pdf
- Bacs - AUDDIS (accurate as of October 2026) https://www.bacs.co.uk/bacs-schemes/direct-debit/services/auddis/
- Pay.UK (Direct Debit) - The Direct Debit Guarantee (accurate as of October 2026) https://www.directdebit.co.uk/direct-debit-explained/direct-debit-guarantee/
- Adfin Help Center - Bulk-migrate your direct debit mandates to Adfin (10+ mandates) (accurate as of October 2026) https://support.adfin.com/en/articles/12688044-bulk-migrate-your-direct-debit-mandates-to-adfin-10-mandates
