Correction: In an earlier version of this story, the initial health-care enrollment estimates were incorrectly reported as just in the month of October. The estimates were actually for October and November. This version has been corrected.

A Dec. 3, 2013, photo shows a woman in Washington, D.C., reading a message indicating that a connection cannot be established with the insurance marketplace site. (Karen Bleier/AFP/Getty Images)

Obama administration officials announced Friday that the enrollment records for an estimated one in four Americans who chose health plans through the online federal marketplace in October and November had computer-generated errors that complicated their ability to finish buying coverage. Officials said that such errors have now become less common.

Currently, the Web site,, is making mistakes in the records of an estimated one in 10 people signing up for a health plan, according to Julie Bataille, director of communications for the Center for Medicare and Medicaid Services, the agency that oversees the federal health-insurance exchange.

Bataille emphasized that the 25 percent error rate for October and November — the exchange’s problem-ridden first two months — and the smaller current number are preliminary, drawn from a sample of enrollments. She said that more precise numbers will not be available until the CMS and insurers finish cross-checking enrollment lists to make sure that health plans know who has signed up for coverage.

Flawed enrollment records have been a major concern to insurers selling health plans through the federal health exchange — and it has important implications for consumers. The records, known as 834 forms, are supposed to be sent early every evening from the federal online system to each participating health plan to notify them of whom their new customers are. From there, insurers send each customer a bill. After that, consumers must pay the first month’s insurance premium before their coverage begins.

In announcing the preliminary 25 percent error rate for the first two months, Bataille did not specify the total enrollments for that period. Federal figures have shown that nearly 27,000 people signed up from Oct. 1 through Nov. 2.

Insurers are now working with CMS to try to resolve a variety of errors that have plagued the enrollment records. In some instances, the system was not sending insurers records of people who had enrolled. Other errors have included duplicative enrollment and cancellation notices for the same person, incorrect information about family members and mistakes involving federal subsidies.

Once the online system is working more fully, it will include an automated way — called “reconciliation” — for the government and participating health plans to compare their lists of who has signed up. That process is supposed to start the middle of this month, but the required part of the system is not yet built. In a two-hour webinar on Friday with about 600 insurance industry representatives, CMS officials said that the agency plans early next week to send each participating health plan a computer file containing the government’s list of who has signed up for that plan between Oct. 1 and Nov. 30. The officials told the insurers that the agency will send out a second list — for December — immediately after a Dec. 23 deadline for consumers to sign up if they want their coverage to begin Jan. 1.

Under this interim method of making sure that the government and health plans agree on who the customers are, insurers will be responsible for comparing the CMS list against their own roster. Some large insurers may be able to perform this comparison electronically, but many may end up having to compare the lists by hand. During the webinar, some insurers complained that this chore would be cumbersome.

Meanwhile, the Obama administration is making headway on a Spanish-language version of the Web site that was supposed to be ready by Oct. 1 but has not been available. Health and Human Services spokeswoman Joanne Peters said that is scheduled to go live Friday night. Administration officials are asking some Latino advocacy groups to provide feedback.

Sandhya Somashekhar contributed to this report.