When the Office of Personnel Management unveiled its new health insurance plan last year during open season, it was tough to tell what the reception would be.

Self-Plus-One — named because it provided insurance to a beneficiary and a dependent, as opposed to family or single coverage — garnered a lot of anticipation, followed by confusion for some.

Despite being designed to provide a cheaper option than family coverage, the enrollee share of Self-Plus-One premiums were sometimes more expensive for beneficiaries. In other cases, the savings promised might not be much less than family coverage.

But despite what OPM has called "anomalous rates," Self-Plus-One has amassed more than 540,000 beneficiaries in its first year, accounting for more than half of the eligible federal employees and retirees.

In a conference call announcing premium changes for the Federal Employees Health Benefits program, agency officials said that 40 insurance plans in the program still had higher enrollee shares than family coverage plans.

In those cases, OPM Director of Healthcare and Insurance John O’Brien said the agency was actively advising beneficiaries in those cases to remain on their family plans.

"While the number of plans is significant, in terms of overall share of the population, it’s relatively modest," he said.

Walt Francis, author of the annual " Checkbook's Guide to Health Plans for Federal Employees," said that while there are still some cases where Self-Plus-One is more expensive, it presents two-person households with another option for coverage.

"I think the Self-Plus-One premiums have caught up a little less than the family premiums, so there’s every reason to pay attention," he said.

Premiums for the Self-Plus-One plan are set to rise $10.32 on average in 2017, compared to $12.97 for anyone using the family plan.

Francis said that the benefits of the plan should allow for continued growth, but OPM faces the common challenge of preaching the benefits of the program to enrollees who aren’t aware of it.

"There’s an awful lot of people who sit on their couch and watch football games in November and December and don’t undertake that dreaded task of looking at health insurance brochures," he said.

"They don’t even realize that they could be saving money if they switch to Self-Plus-One. So I think we will see more people taking that option over time, but it’s going to take a while."