The website has been plagued by technology problems and has not worked reliably since its launch on October 1, embarrassing the administration and providing ammunition for Republicans seeking to roll back the law known as Obamacare.
The application, enrollment tools, and "data hub" will not be available from about 7 p.m. Moutain Time on Saturday until 7 a.m. Mountain Time on Sunday, a spokeswoman for the department said in a statement, telling consumers they can call a toll-free call center to apply for insurance in the meantime.
"The HealthCare.gov tech team is performing extended maintenance this weekend to improve network infrastructure and make enhancements to the online application and enrollment tools," said Joanne Peters, the spokeswoman.
The administration has said it will fix the site by the end of this month. The government hopes that about 7 million people enroll for insurance by the end of March under the law passed in Obama's first term to expand access to health insurance and require that people have coverage or pay a fine.
The administration said it expects early enrollment numbers to be low, in part because of the website's problems. Documents released this week by a U.S. House of Representatives committee showed only 248 Americans had signed up in the first three days the site was running.
The administration has said it will not release enrollment statistics until mid-November.