Domestic
PAYMENTS SIGNAL · REFERENCE CARDBacs Direct Debit
A biller pulls a bill from a customer's account over Bacs' three-working-day cycle under a Direct Debit Instruction, with unpaid items returned through the ARUDD cycle a day or two after settlement.
Actors
- Riya (payer)customer
- Bank Alfa (payer bank)bank
- Bacs (Pay.UK)infrastructure
- Nordbank (collector bank)bank
- Asha Traders (collector/biller)customer
Messages
- Bacs Standard 18 collection file
The sequence
| # | Step | Route | Kind |
|---|---|---|---|
| 1 | Direct Debit Instruction — A mandate already exists | Riya → Asha Traders | internal |
| 2 | Day 1 — submit — Asha Traders submits the collection file | Asha Traders → Bacs | message |
| 3 | Day 2 — process — Bacs processes and passes entries to the banks | Bacs | clearing |
| 4 | Day 3 — settle — The banks settle in central bank money | Bank Alfa → Nordbank | settlement |
| 5 | Day 3 — DR Riya — Riya's account is debited | Bank Alfa | posting |
| 6 | Day 3 — CR Asha Traders — Asha Traders' account is credited | Nordbank | posting |
Exception rails
| Rail | Trigger | Where the money ends up | Next action |
|---|---|---|---|
| ARUDD: unpaid Direct Debit | When Bank Alfa tries to pay the item, Riya's account has insufficient funds or her mandate has been cancelled, so the Direct Debit cannot be paid. | GBP 90.00 stayed with Riya — either the debit never stuck because Bank Alfa refused to pay, or any provisional entry was reversed by the return. · The collection did not complete for this item; the unpaid return unwinds it through the ARUDD cycle on days 4-5, after normal settlement day. | Bank Alfa — Asha Traders contacts Riya to arrange payment or re-present the Direct Debit on a future cycle if the mandate is still live. |