Staff members were told not to rely on data from the troubled healthcare exchange, called DC Health Link or DCHL, the report said.
The Hill said it obtained an email sent to staffers Wednesday telling them "it is essential that you confirm your coverage in DCHL through the Disbursing Office," adding, "Do not rely on your 'My Account' page or other correspondence from DCHL."
"Please do not assume you are covered unless you have seen the confirmation letter from the Disbursing Office," the email said.
Capitol Hill employees had a Monday deadline to sign up for healthcare in Washington, where members of Congress and their staffs are eligible for a generous healthcare subsidy from the government, the newspaper said.
The Hill reported the email said staff members who were not able to enroll because of technical difficulties now have until Dec. 16 to sign up.
The Centers for Medicare and Medicaid Services said as much as 25 percent of enrollment transmissions sent from the federal portal, healthcare.gov, to insurers were either garbled or contained bad data, The Hill reported.
The report said based on government enrollment figures, up to 30,000 applications might need to be re-evaluated before the end of the year.