The Medicaid program continues to waste billions of dollars a year by failing to eliminate improper payments to states despite government recommendations to do so.

Medicaid’s long-standing problem with enrolling providers has emerged as one of the chief culprits of the wasteful spending, along with correctly identifying providers.

The improper spending stands to keep growing as states expand their Medicaid programs under Obamacare provisions, adding to government losses.

The program has perennially been classified as high-risk by the Government Accountability...