My children and I are tribal members, but my spouse is not. Can we enroll as a family with a Special Enrollment Period?

If your state uses the federal Marketplace, yes. If one family member on the application is eligible for the Special Enrollment Period (SEP), all family members who apply on the same Marketplace application are eligible. This is true even if different family members are eligible for different Marketplace plans, based on differing eligibility for lower monthly premiums or out-of-pocket costs.