A depository institution may calculate interest on the daily or average daily ledger or collected balance in an account for the statement period, provided that the method of calculation used is consistent with the method of interest calculation applied by the institution to individual accounts of the same type, size and duration. This interest may be calculated on an annual, monthly or other periodic basis within a 12 month period ending on December 31.
Wis. Admin. Code Department of Administration Adm 91.04