WASHINGTON » The federal agency that had trouble launching a health insurance website last fall has a massive new project. Any glitches on this one could delay tax refunds for many Americans.

Because of complicated connections between the new health care law and income taxes, the Department of Health and Human Services must send out millions of new tax forms next year. They’re like W-2s for people getting health insurance tax credits under President Barack Obama’s law.

The forms are called 1095-As, and list who in each household has health coverage, and how much the government paid each month to subsidize those insurance premiums. Nearly 5 million people have gotten subsidies through HealthCare.gov. If the forms are delayed past their Jan. 31 deadline, some people may have to wait to file tax returns — and collect their refunds.

A delay of a week or two may not sound like much, but many people depend on their tax refunds to plug holes in family finances.

The uncertainty is unnerving to some tax preparation companies, which try to run their filing season operations like a military drill. The Obama administration says it’s on task, but won’t provide much detail.

States operating their own health insurance marketplaces also will have to send out the new forms, even if they had website problems.

(Officials with Hawaii’s health insurance exchange — Hawaii Health Connector — do not know how many people in the state have received tax credits or the average amount of the credits.)

But the biggest job belongs to the federal exchange serving 36 states. HHS will have to manage that while in the midst of running the 2015 health insurance sign-up season, when millions more are expected to try to get coverage.

"It’s very unrealistic to expect that they would be able to implement a process that distributed these forms in the middle of open enrollment, and on time," said George Brandes, vice president for health care programs at Jackson Hewitt Tax Service.

The average tax refund is about $2,690, and people who count on getting money back often file early.

Liberty Tax Service vice president Chuck Lovelace said his company is giving the feds the benefit of the doubt, but the possibility of delays "is not something we can turn a blind eye to."

"It could have a dramatic impact on our customers," Lovelace said. "The tax refund is the largest check many consumers get."