Marilyn Tavenner, top administrator for Centers for Medicare & Medicaid Services (CMS), has announced that she is stepping down from her position at the end of February. Tavenner had served as acting administrator of CMS since late 2011, and was confirmed in May 2013 as the permanent chief of the agency.

In a letter to staff, Tavenner said the agency has accomplished a lot over the past few years, such as helping to implement the Affordable Care Act and improving operations across the agency. “You are truly transforming health care in this country,” she wrote to employees.

Andy Slavitt, currently CMS’s principal deputy administrator, will become acting administrator.

Before joining CMS in 2010 as its principal deputy administrator, Tavenner served as secretary of health and human resources for the state of Virginia. She previously spent most of her career with the Hospital Corporation of America, starting as a staff nurse and becoming CEO of two hospitals and then group president of outpatient services. She also served as chairman of the Virginia Hospital Association.

Tavenner served on the AHA board, leaving it in 2005 to become Virginia’s secretary of health and human resources.