N.D. Cent. Code § 57-39.4-30: (329) Effective date for rate changes

Each member state shall provide that 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.

2.For a rate decrease, the new rate shall apply to bills rendered on or after the effective date.