Bacs Approved Software Provider

A Service User Number, or SUN, is the unique six-digit number that identifies your business to Bacs when you pay or collect money through the scheme. Every Direct Debit you collect and every Direct Credit you pay carries it. You apply through a sponsoring bank, which assesses your trading history, financial standing and how you intend to use the scheme.

You need your own SUN for either route (software or a Bacs approved bureau). A bureau submits under your number; it does not lend you one. If a Service User Number is not available to you yet, Direct Debit facilities management is the arrangement that lets you collect under a provider’s number instead, and we will introduce you to a specialist partner for that.

One change is worth planning for now. Bacs has confirmed that from 1 July 2027, payment service providers will no longer create new Non-AUDDIS Service User Numbers. AUDDIS is the Automated Direct Debit Instruction Service, which lodges Direct Debit Instructions electronically rather than on paper.

Any SUN created after that date will only be able to lodge instructions using AUDDIS.

If you already hold a Non-AUDDIS SUN, nothing stops working. You can still lodge new Non-AUDDIS instructions on it and carry on collecting from the instructions you hold. What changes is that you cannot ask your sponsor for a new Non-AUDDIS SUN after that date, so a business planning to add a second SUN for a new trading entity should plan for it to be AUDDIS.

InterPay is a “file agnostic” software meaning that you can use payment files from any software. Online and digital customer sign-up portals can be branded to align with your business identity. From standard manual uploads through to full unattended automation and approval, Interpay software is a universal BACS submission software.

Interbacs has supplied Bacs software since 2003 and was one of the first Bacs Solution Suppliers in the UK. Approval is not a one-off: it is re-tested as the scheme changes, and a supplier that stops meeting the requirement comes off the register.

• Bacs Approved Software
• Bacs Approved Bureau
• Bacs Electronic Elements Affiliate
• ISO 9001:2015 and ISO 27001:2022 certified, registered with the ICO, and Cyber Essentials assessed.

Through Bacstel-IP, the secure channel every Bacs submission travels over. Your software builds the payment file, signs it with a digital certificate held either in software or on a hardware security module, and transmits it. The three-day cycle then runs: input day, processing day, entry day.

Bacstel-IP is the part of the process that makes approved software necessary rather than merely sensible. Certificate handling, file validation and the reports that come back are all managed by the product. Those reports are worth knowing by name, because they are what tells you a collection has gone wrong:

ARUDD: the Automated Return of Unpaid Direct Debits, telling you which collections failed and why.

ADDACS: the Automated Direct Debit Amendment and Cancellation Service, telling you which mandates a payer has changed or cancelled.

AUDDIS: the Automated Direct Debit Instruction Service, used to lodge new Direct Debit Instructions electronically.

AWACS: Advice of Wrong Account for Automated Credits, telling you a Direct Credit went to an account that has since changed.

Software that only submits, and leaves you to read those reports by hand, is doing half the job. Acting on them promptly is a scheme requirement as much as an operational one.

InterPay — Bacs approved submission software

InterPay builds and submits Direct Debit and Direct Credit files over Bacstel-IP, handles the returned reports, and supports multiple Service User Numbers where a group collects for several trading entities. It is available on your own servers or hosted, and it is the product most Interbacs customers start with.

DDMS — Direct Debit Management Software

DDMS is the layer above submission. It manages the mandates themselves: setting up new payers, applying advance notice, changing collection dates and amounts, tracking failures through to resolution, and reporting on the whole collection cycle. If InterPay is how the file reaches Bacs, DDMS is how you run the operation that produces it.

InterPass — identity verification

InterPass checks that the person setting up a Direct Debit is who they say they are, and that the account they have given belongs to them. Paperless Direct Debit sign-up carries an obligation to verify, and InterPass is how that obligation is met without adding a manual step to your sign-up flow.

Hardware Security Modules

A hardware security module holds your Bacstel-IP signing certificate in tamper-resistant hardware rather than on a workstation. Larger submitters and businesses with formal security requirements generally want one; smaller submitters generally do not need one.

For the submission, yes, you can use our Payroll Bureau Software. Bacs is how salaries reach employee accounts as Direct Credits, and InterPay submits a payroll Bacs file exactly as it submits a collection file. Businesses running their own payroll in-house use it to pay staff, suppliers and expenses on the same schedule.

What it does not do is calculate the payroll. Interbacs supplies the Bacs submission component for teams already running payroll in a package such as Sage, Xero or BrightPay. It does not work out gross to net, it does not handle RTI filing to HMRC, and it is not a payroll suite. If that is what you are looking for, it is a different product from a different market and we will say so.

Where a business wants the payroll run itself handled as well, that is our managed payroll bureau service rather than our software.