39 C.F.R. § 3040.105

(a) Whenever the Postal Regulatory Commission issues a final order that modifies the Mail Classification Schedule, it shall update the Mail Classification Schedule appearing on its website at http://www.prc.gov in accordance with paragraph (b) of this section.

(b) Modifications to the Mail Classification Schedule shall be incorporated within 6 months after the modifications take effect pursuant to the applicable final order that modifies the Mail Classification Schedule.

(c) Modifications pending incorporation into the Mail Classification Schedule are effective immediately upon written direction from the Postal Regulatory Commission.