64:01:01:52Effective date of rate changes.

The effective date of rate changes for services covering a period starting before and ending after the statutory effective date shall be as follows: (1) For a rate increase, the new rate shall apply to the first billing period starting on or after the effective date; and (2) For a rate decrease, the new rate shall apply to bills rendered on or after the effective date.

Source: 29 SDR 177, effective July 2, 2003.