- The reference used in a Direct Debit Instruction may be up to 18 characters long and must be a minimum of 6 characters.
- It must be lodged with the paying banks exactly as it appears on a signed DDI.
- It must be unique for the sort code, account number and SUN to ensure that the paying banks can accurately match Direct Debits to DDIs.
- Collections from an AUDDIS Direct Debit Instruction must contain the ‘core reference’ and may also contain a variable element, identifying that particular claim. (The variable element is as added to the end of the reference i.e. a suffix not a prefix).