In the overpayment dispute, health plans want CMS to scale back — if not kill off — an enhanced audit tool that, for the first time, could force insurers to cough up millions in improper payments they've received. (Photo: Shutterstock)

Health insurers that treat millions of seniors have overcharged Medicare by nearly $30 billion the past three years alone, but federal officials say they are moving ahead with long-delayed plans to recoup at least part of the money.

Officials have known for years that some Medicare Advantage plans overbill the government by exaggerating how sick their patients are or by charging Medicare for treating serious medical conditions they cannot prove their patients have.

Getting refunds from the health plans has proved daunting, however. Officials with the Centers for Medicare & Medicaid Services repeatedly have postponed, or backed off, efforts to crack down on billing abuses and mistakes by the increasingly popular Medicare Advantage health plans offered by private health insurers under contract with Medicare. Today, such plans treat over 22 million seniors, more than 1 in 3 people on Medicare.