32 pages. "Last year, employer-sponsored group health plans ... were responsible for most of the nearly $183 million in outstanding Medicare secondary payer (MSP) debt. MSP debts arise when Medicare inadvertently pays for services that are subsequently determined to be the financial responsibility of another. The Centers for Medicare & Medicaid Services ... administers Medicare with the assistance of about 50 contractors that, as part of their duties, are required to recover MSP debt." [GAO-04-783, published Aug. 20, 2004, released Sept. 20, 2004]