If the Secretary does not take action to approve or disapprove a compact or amendment within the 45-day review period, the compact or amendment is approved by operation of law, but only to the extent the compact or amendment is consistent with the provisions of IGRA. The Secretary will issue a letter informing the parties that the compact or amendment has been approved by operation of law after the 45th day and before the 90th day. The Secretary's letter may include guidance to the parties reflecting the Department's interpretation of IGRA. The compact or amendment that is approved by operation of law becomes effective only upon publication in the Federal Register.