The Jan. 5 deadline to pay for health insurance through the state’s new health benefit exchange has been extended for another 10 days by Covered California insurers.

Health insurance companies Saturday agreed to jointly allow anyone who signed up for insurance coverage starting Jan. 1 through the exchange to pay for that coverage by Jan. 15.

The original deadline to pay premiums was Jan. 1. The exchange board last month extended that deadline to Jan. 5. The latest agreement with 11 health insurance companies gives enrollees a little longer grace period.

So far, according to a preliminary estimate by Covered California executive director Peter Lee, roughly 400,000 Californians signed up for coverage through the exchange by Dec. 22, the day before the deadline set for individuals to receive coverage on Jan. 1, 2014.

The exchange’s open enrollment period continues until Mar. 31 so Covered California is still soliciting applications for coverage. The deadline extension is just for early enrollees eligible for Jan. 1coverage.

The exchange has not yet released data on the number of enrollees who actually paid their premiums. Later this month, Covered California officials are expected to release official data on the number of enrollees from Oct. 1 until Dec. 23.

Because so many Californians signed up in December, they may not have had time to receive invoices and send in premium payments, exchange officials said in explaining the deadline extension.  Payments need to be received by insurers by Jan. 15^, not just postmarked by that date, exchange officials said.