Abstract: A system and method for determining eligibility for reimbursement for medical claims for patients may be implemented with computer software which compares a service provider's patient information against a benefit provider's database of covered persons to determine if the patient is eligible for benefits. The service provider records may be compressed by grouping all of the medical claims relating to a particular patient into one cluster represented by a composite medical claim, which may be used to query the benefit provider databases to determine if the patient is recognized. If the patient is recognized, every record within the cluster may be checked against the benefit provider's database to determine whether one or more patient medical claims are eligible for reimbursement.