Congress established the Medicaid Buy-In program when it passed the Balanced Budget Act (BBA) of 1997 and the Ticket to Work and Work Incentives Improvement Act (Ticket Act) of 1999. Under the program, so named because participants "buy into" Medicaid by paying monthly premiums or co-payments, states can offer Medicaid coverage to workers with disabilities whose income and assets would otherwise make them ineligible for Medicaid. To enroll in the program, individuals must have a disability as defined by the Social Security Administration (SSA) and meet certain work and financial eligibility requirements.

Since its inception, the Medicaid Buy-In program has offered state policymakers an important option for providing health care coverage to working adults with disabilities. More than 200,000 people have enrolled in the program at some point between 1997 and 2007, and as a result, have access to health services covered by their state Medicaid plans. Most Buy-In participants are also covered by Medicare because they receive Social Security Disability Insurance (SSDI) payments. Analyzing the Medicaid and Medicare expenditures of Buy-In participants offers useful information to policymakers and program administrators who are interested in monitoring spending trends for future budget and outreach planning. It can also foster a better understanding of how service needs vary among Buy-In participants. This information can help states to ensure their Buy-In programs will continue to meet the on-going needs of workers with disabilities.