SDD CORE and SDD B2B are the two SEPA Direct Debit schemes. They share the same pain.008 message envelope, but the rulebook around them is entirely different — the choice of variant cascades into lead-times, refund rights, and onboarding flow.
SDD CORE is the consumer-facing default. Refund rights are wide: 8 weeks for any authorised collection (no questions asked), extended to 13 months for an unauthorised collection. Lead-times are 5 banking days for the first collection (FRST) and 2 for subsequent ones (RCUR). The mandate can be paper-based or electronic; e-mandate flows are supported but not mandatory.
SDD B2B is the corporate-to-corporate scheme. Refund rights are zero — once the collection clears, it is final. To compensate, the debtor bank is required to confirm the mandate with the debtor *before* honouring the first collection (the "B2B mandate confirmation" step), and only an SCT-registered corporate entity can be the debtor. Lead-times are tighter at 1 banking day for both FRST and RCUR.
The pain.008 difference is the LclInstrm code: CORE vs B2B. iso-compliant validates that the (variant, debtor-type, lead-time) tuple is consistent at build time — emitting a B2B pain.008 with a consumer-tagged debtor is rejected before submission. See apps/api/src/lib/pain008-builder.ts.
A common cross-border surprise: SDD B2B requires the debtor to *opt in* with their bank to receive B2B direct debits at all (it is not on by default). A creditor who switches a recurring CORE mandate to B2B without coordinating with the debtor will see the first B2B collection reject as "debtor not enrolled in B2B".