There is nothing in HIPAA (Health Insurance Portability and Accountability Act) that would prevent them from releasing a policy number or ID card to her if they've confirmed that she has coverage and they previously accepted a reasonable request to restrict the use and disclosure of her address and/or to accomodate an alternative address. Quite the contrary, part of HIPAA would have been to facilitate this situation. You need to request a copy of their Notice of Privacy Practices which they are required to give her under federal law. This notice should describe the rights she has to Access her health records, Amend her health records, make a request for a reasonable Accomodation (such as an alternate address, which happens frequently with minor children in divorce situations). There is also a right to request a Restriction on use and disclosure of her health information, if for example, release of that information to her dad could potentially endanger her. I am not sure if your sister requested an accomodation or a restriction. The notice will also provide you with the name of the specific individual who acts as the Plan's Privacy Official. This person is typically, but not always, someone at the employer's office and that is who you should be talking to. If "the Plan" previously agreed to an accomodation or restriction, changing insurance carriers does not terminate the Plan's responsibility to honor that agreement. I suspect they are not calling you back because they are confused with how HIPAA applies or because they know a mistake has been made. There are a few other laws that may impact you. You need to know if a Qualified Medical Child Support Order (QMCSO) is in place and has been accepted by the employer. If yes, this order may name the acceptable "alternate beneficiary" for sending notices, benefit information, checks and that alternate beneficiary might be your sister. You need to know if the employer has sent the National Medical Support Notice to the insurance carrier notifying them of the QMCSO. You also should look into whether the QMCSO ends at age 18, and remember under health care reform, she could be eligible to age 26 if you were able to get the QMCSO amended. You may want to look into this because it is likely much less expensive then if you were to try to buy individual coverage for her and she does have a medical condition that might rate her coverage higher and/or be subject to pre-ex. Lastly, if she is dropped from coverage at age 18 under the QMCSO (if nothing is done to amend it), or once she turns 26 (if the QMCSO is amended), she will be entitled to COBRA coverage for 36 months after that which is self pay, but again typically cheaper/more comprehensive than what is available in the individual market. She would need to take the COBRA coverage for the full 3 years in order to be "HIPAA qualified" (this is another provision of HIPAA that protects the portability of coverage from one plan to another) and have her not refused for coverage by an individual plan as well as have pre-ex waived under the individual plan. One thing that hurts you here is pretending to be your sister to make this stuff happen. It may be worth seeing an attorney. Good luck to you and thanks for stepping in to help your niece, sounds like she needs a responsible adult in her life.