In response, she gave a detailed timeline of the ObamaCare deadlines that officials expect to meet over the next six months, including the announcement of participants in the law's "navigator" program on Aug. 15; the completion of end-to-end testing of the exchange enrollment system by the end of August; and the release of the final exchange application by the end of August.
Tavenner also said that insurance rates for the federal exchange will be available in September. That marketplace encompasses all the states that refused to create their own exchanges.
In back-and-forth with lawmakers, Tavenner said live testing of the exchange enrollment system is 80 percent complete and involves all the agencies necessary for verifying applicants' information.
"As we've identified any vulnerabilities, we have corrected them," Tavenner told members of the House Energy and Commerce Committee. "So right, now we are in good shape."
Trial runs of the exchange's payment system will take place in September through December, and no tech contractors have asked for delays, she said.
The exchanges are ObamaCare's centerpiece and crucial to the law's mission of extending health insurance to millions of patients.
As of this spring, 27 states refused to create their own marketplaces, ceding the task to federal officials.