Tribal Tax and Investment Reform Act of 2021 This bill treats Indian tribal governments as states for purposes of the annual allocation of the tax-exempt bond volume cap. It also repeals provisions that limit an Indian tribal government's eligibility to issue tax-exempt bonds or to be exempt from specified excise taxes to transactions involving the exercise of an essential government function customarily performed by state and local governments. The bill (1) treats employee benefit or pension plans maintained by Indian tribes and domestic relations orders issued pursuant to tribal law in the same manner as plans maintained by states and domestic relations orders issued pursuant to state law; and (2) treats tribal charities and foundations in the same manner as charities and foundations funded and controlled by other governmental entities for purposes of the tax-exempt status of, and deduction for contributions to, such organizations. The bill gives Indian tribes or tribal organizations access to the Federal Parent Locator Service if they are eligible for a grant to operate a child support enforcement program. It makes those tribes and tribal organizations eligible to participate in the program that collects past-due support from individual tax refunds. An Indian tribal government may determine whether a child has special needs for the purpose of the tax credit for the adoption of a child with special needs.