Medicaid Coverage for Addiction Recovery Expansion Act This bill allows state Medicaid programs to cover residential addiction treatment facility services for adults between the ages of 22 and 64 if such services are offered as part of a full continuum of evidence-based treatment services. Residential addiction treatment facility services are medically necessary inpatient services provided in an accredited, size-limited facility for the purpose of treating a substance-use disorder within a specified time period. In addition, the bill establishes a grant program for states to expand infrastructure and treatment capabilities of existing youth addiction treatment facilities that (1) provide addiction treatment services to youths under Medicaid or the Children's Health Insurance Program (CHIP), and (2) are located in communities with high numbers of medically underserved populations of at-risk youths. At least 15% of grant funds awarded to a state must be used for making payments to rural facilities.