I believe it holds both current balance and previous balance,,, see below (from central bank)
The Central Credit Register will hold information about loans existing on 30 June 2017 and any new loans after that. From then, lenders will also send the Central Credit Register monthly updates on the status of loans. The type of credit information that the Central Credit Register will store includes the:
- amount of all loans; - type of each loan – such as credit card, mortgage, overdraft or personal loan;
- name of each lender; -outstanding balance; - number of overdue payments if any; and -date of next payment.