AUDDIS Mandate Submission to Modulr

When a tenant completes the mandate setup form, the Direct Debit service automatically submits the mandate to Modulr via the AUDDIS scheme. This page describes how that flow works, what happens on success or failure, and what notifications are sent.

Overview

AUDDIS (Automated Direct Debit Instruction Service) is the BACS scheme used to electronically register new Direct Debit mandates with a payer's bank. Once a mandate is submitted and accepted, it becomes active and eligible for scheduled collections.

The submission is handled by a background Inngest function that is triggered automatically when a tenant submits the final step of the mandate form. The flow is fully asynchronous — Modulr processes the AUDDIS submission and returns a result via webhook callback.

Submission Flow

Tenant completes mandate form
        │
        ▼
Inngest function triggered
        │
        ▼
Mandate submitted to Modulr (AUDDIS)
  - Tenant bank details
  - Service User Number (SUN)
  - Collection amount
  - Payment frequency
  - Collection day
        │
        ▼
Mandate status set to: pending
        │
        ▼
Modulr processes AUDDIS submission
        │
   ┌────┴────┐
Accepted    Rejected
   │             │
Status:      Status:
active       failed
             + reason
   │             │
   └────┬────┘
        ▼
Email sent to agent + tenant

What Gets Submitted to Modulr

The following fields are included in every AUDDIS mandate submission:

Field	Description
Account number	Tenant's bank account number
Sort code	Tenant's sort code
Account holder name	Name on the tenant's bank account
SUN	The agent's Service User Number, scoped per customer
Amount	The agreed collection amount in GBP
Frequency	Payment frequency (e.g. monthly)
Collection day	The day of the month funds will be collected

Mandate Status Transitions

On Acceptance

When Modulr's webhook confirms AUDDIS acceptance:

Mandate status is updated to active.
The mandate becomes eligible for scheduled BACS collection runs.
An acceptance notification is sent to the agent and tenant.

On Rejection

When Modulr's webhook reports AUDDIS rejection:

Mandate status is updated to failed.
The rejection reason provided by Modulr is recorded against the mandate record.
A rejection notification is sent to the agent and tenant, including the reason.
The agent can re-send the mandate invite to the tenant to restart the process.

Email Notifications

Both the agent and the tenant receive email notifications on mandate acceptance and rejection.

Event	Agent notified	Tenant notified
AUDDIS accepted	✅	✅
AUDDIS rejected	✅ (with reason)	✅ (with reason)

Notes

AUDDIS submission is asynchronous. There is a window between form completion and final mandate activation while Modulr processes the instruction with the BACS scheme.
Mandates in pending state are not eligible for collection until they transition to active.
If a mandate is rejected, no funds will be collected. The agent must take action to resolve the issue (e.g. verify bank details and re-issue the mandate invite).