Okla. Stat. tit. 68, § 68-1354.25: Effective date of state or local sales and use tax

rate changes.

The effective date of state or local sales and use tax 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.