Starting a family can be an exciting time but it is important to adjust your health benefits so that everyone is always covered. But just like everything else with the government, this is not quite as simple as you might hope.
The first question we have to answer is who qualifies as a child that can be covered under your plan? Qualifying children include children under age 26, adopted children, natural children born out of wedlock, stepchildren, and foster children (the rules are a little more complicated for foster children so I would encourage you to research the rules if you'd like to add a foster child to your plan). Also, to be covered under the FEHB program the children need a state-issued birth certificate that claims you as a parent.
Having a child is considered a qualifying event which allows you to change your benefits even if it is not open enrollment. You would be able to change your enrollment between self only, self plus one, or self and family. You would also be able to switch to another FEHB plan if desired. Employees that are not currently enrolled in FEHB would also be able to enroll because of the birth of a child. If you are already retired, this life event would not allow you to re-enroll.
Once a child turns age 26 they are no longer eligible to stay on their parents plan (unless they have a qualifying disability). At that point they can continue coverage through FEHB for up to 36 months but they will have to pay the full premium plus 2% for admin fees. After that they would then have to get their own coverage. The parents would then be able to switch their enrollment to self only, self plus one, or continue with self and family depending on what is applicable for their family. The parents have a window of about 90 days to change their coverage. This window allows for 30 days before and 60 days after your child turns 26. It is up to the parents to notify their agency once a child is no longer eligible. For a retiree they will have to talk to OPM.
Parents would be able to remove a child from their plan before age 26 if their child is eligible for their own help plan through their employer. Generally, the child must be at least 18 for this to be possible. This would only make sense if the family could then downgrade coverage from family coverage to self plus one for example.
All this may seem quite complicated but it gets better as you learn more about it. FEHB is an incredible benefit and knowing the rules will help extend this benefit to your entire family.