House Oversight Committee Chairman James Comer is raising concerns about the lack of transparency and complexity of the federal coding and billing systems for Medicare and Medicaid, and how those are possibly enabling significant waste, fraud and abuse of taxpayer money. 

Comer, a Kentucky Republican, sent a letter Thursday to Administrator Mehmet Oz of the Centers for Medicare and Medicaid Services, which manages those billing and coding systems, asking him to prepare for a staff-level briefing as part of an investigation into the issue. 

"The Current Procedural Terminology (CPT) code system mandated by the federal government as the standard for billing Medicare and Medicaid plays a central role in determining how billions of taxpayer dollars are spent each year. The complexity of this system may be contributing to improper billing and higher costs for patients and taxpayers," Comer said in the letter. 

The letter gives a deadline of May 7 for the briefing.