Between May 1 and June 30, 2009, insurers subject to the Medicare Secondary Payer (MSP) mandatory reporting provisions included in the Medicare, Medicaid and SCHIP Extension Act of 2007 must register electronically with the U.S. Centers for Medicare and Medicaid Services (CMS). These reporting requirements imposed by CMS are an effort to better enforce existing MSP laws and are triggered where Medicare is the secondary payer to some other primary liability insurer for an injury or illness. Why should affected insurers care? In a word, penalties. Insurers subject to these requirements must submit claims data starting in the fourth quarter of 2009, or risk civil monetary penalties of $1,000 a day for each individual for whom they should have submitted claims information. For further information, see the MSP Mandatory Reporting User Manual available at