Intergovernmental Tax Agreement Act of 1999

[AI summary unavailable — showing source text] Intergovernmental Tax Agreement Act of 1999 - Grants U.S. consent to States and Indian tribes to enter into intergovernmental compacts and agreements concerning the collection and remittance of : (1) applicable State taxes on retail commercial transactions involving non-Indians on Indian lands; or (2) covered tribal equivalency taxes. Permits: (1) a tribe to request the Secretary of the Interior to initiate negotiations on that tribe's part with a State for the purpose of entering into a tax compact; and (2) a State to request the Secretary to initiate negotiations between a tribe and the State to enter into such a tax compact. Requires: (1) a request by a tribe or State to be in writing; (2) the Secretary to issue a written response within 30 days after receiving a request to the submitting tribe or State; (3) the Secretary to commence negotiations with respect to the tax compact that is the subject of the request submitted by the tribe or State within 30 days after receiving such request; and (4) the parties to complete the negotiations within 120 days, unless the parties agree to an extension. Directs the Secretary to initiate a mediation process, with the goal of achieving a ta…