From NPR:
Under the Affordable Care Act, members of the U.S. House of Representatives, the Senate and their office staffs who want employer coverage generally have to buy it on the health insurance exchange. Before the ACA passed in 2010, they were eligible to be covered under the Federal Employees Health Benefits Program. (People working for congressional committees who are not on a member’s office staff may still be covered under FEHBP.)
The members of Congress and their staffs choose from among 57 gold plans from four insurers sold on the DC Health Link’s small business marketplace this year.
Approximately 11,000 are enrolled, according to Adam Hudson, a spokesperson for the exchange. The government pays about three-quarters of the cost of the premium, and workers pay the rest. They aren’t eligible for federal tax credits that reduce the size of insurance premiums.