Addition of a self plus one option to the FEHB likely will be attractive to retirees who have only one eligible family member and who would save money by switching from family enrollment, according to OPM.

OPM plans to make self plus one available in the 2016 plan year, recently proposing rules with the goal of finalizing them well before this fall’s open season for electing next year’s coverage.

For a married retiree, a spouse commonly is the only eligible family member—children’s eligibility ends at age 26 unless the child is disabled—and enrollment in family coverage in effect means subsidizing enrollees who have two or more eligible family members on their enrollment. Said OPM in its rules: “A large percentage of annuitants who currently have self and family coverage would likely benefit from a self plus one premium tier.”

“Because the self and family option includes coverage for a larger number of people, a natural assumption would be that premiums (both the portion paid by the government and the portion paid by the federal employee or annuitant) would be lower with self plus one enrollment than with self and family enrollment,” it said.

However, that raises the question of the impact on those—both active and retired–with multiple eligible family members who would stay with family coverage. By the same logic, OPM noted, the shift of some currently in family coverage to self plus one would mean an increase in family coverage premiums as family plans on average will be covering a larger number of people than currently.

In some cases, it said, the increase may be large enough to drive enrollees to other insurance options, such as a spouse’s health plan from a private sector employer.

On the other hand, it said, some enrollees currently have self-only coverage even though they have a spouse who would be eligible under family coverage rules; in many cases, that again would be a spouse eligible through another plan through his or her employment. That couple may currently have two separate self-only policies because they are less expensive than FEHB family coverage. Such a couple may choose FEHB self plus one coverage when it becomes available.

OPM said it cannot predict the impact on premiums but will be watching that issue.