If a utility uses a future test year in a rate case, the utility shall provide the information required by Section 325.30 for each of the three consecutive calendar years immediately preceding the test year for which actual data are available, provided, however, that for those past calendar years this Section shall not be construed as imposing additional information requirements that did not exist prior to the effective date of this Part.
Ill. Admin. Code tit. 83, § 325.50