LANSING (AP) — Gov. Gretchen Whitmer called Monday for refunds to be swiftly issued to drivers who pay for unlimited coverage of medical bills in car crashes.

In a letter to the Michigan Catastrophic Claims Association, the Democratic governor cited a surplus of $5 billion that she attributed to premium overcharges and cost-saving measures under a 2019 law. She did not specify how much should be returned to motorists.

The MCCA is a state-created nonprofit entity that reimburses car insurers for health care claims surpassing $600,000. Michigan used to require drivers to pay an annual per-vehicle fee that at one point surpassed $220. Now it is optional as of mid-2020.

“The surplus belongs to Michigan policyholders and should promptly be returned directly to them in full, in the form of refund checks,” Whitmer wrote.

The MCCA could not immediately be reached for comment.