Most Individuals plans have a pre-eisting condition eclusionary clause, which is typically 6 months to one year from effective date of coverage. The applies to all pre-eisting medical conditions, whether you disclosed them on your application or not. If an insurance carrier has a concern about a pre-eisting condition that is likely to result in claims beyond the standard eclusionary period, they might also add a rider to your insurance plan. A rider will usually etend the eclusionary period for the condition stated in the rider, but this has to be disclose to you and receive your formal acceptance. Under federal law, any length of time that you were insured prior to enrolling in the BCBS plan must be applied to this eclusionary period. Most health coverage can be used as creditable coverage, including participation in a group health plan, COBRA continuation coverage, Medicare and Medicaid, as well as coverage through an Individuals policy. However, a lapse in coverage of more than 63 days eliminates your ability to apply prior coverage to the eclusionary period. If you did not lapse coverage for more than 63 days, you need to provide BCBS with proof of prior coverage. They may not be aware of your prior coverage, which could be the cause for the claims denials.