OPM told carriers that they are to emphasize that the same enrollee and family member eligibility under family coverage also will apply to self plus one, that enrollees should determine their eligible family members and decide which is best for them, and that self plus one provides coverage only for the enrollee and one eligible family member that the enrollee is to designate. OPM stressed that only legally married spouses are considered eligible and that the change does not extend eligibility to unmarried domestic partners. While it’s generally assumed that self plus one rates will fall between self only and family coverage, to be sure, OPM earlier directed that self plus one rates cannot exceed family rates—as might happen depending on certain assumptions about enrollment patterns and levels of consuming health care. FEHB rate announcements typically are made in late September to early October in advance of the benefits open season, which this year runs November 9-December 14.