Update guidance for Banking account rate detail

[nils-work]

Description

Guidance on the BankingAccountDetail schema provides statements relating to accounts with Single rate, multiple and tiered rates. Participants have raised concerns that the guidance allows important fields relating to account rates to be omitted from responses.

Intention and Value of Change

To support rate analysis and comparison use cases, ensure all details relevant to deposit and lending rates are disclosed.

Area Affected

Although a change to the Standards is not being proposed, it is anticipated that a change to guidance related to the BankingAccountDetailV3 schema could have an impact on live implementations.

Change Proposed

To update the current guidance with the following edits, to clarify that the rate array structure is always required, even when describing only a single rate. This ensures the additional fields including calculationFrequency, applicationFrequency, repaymentType, loanPurpose and additionalValue are always disclosed where applicable.

Single rate, multiple and tiered rates:

• ~~If a product only has a single applicable rate, the array is not required, and the single rate can be provided in the depositRate field or in the lendingRate, as applicable.~~
• If a product has ~~multiple~~ one or more applicable rates, such as tiered deposit rates, then both the array of rate detail and the single rate field are required. The Data Holder (DH) supplies the current effective rate in the depositRate field or in the lendingRate field, as applicable. The DH is expected to know the current effective rate. Clients can read the current effective rate directly, and are not required to parse the full array.