The main purpose of the VA Billing Accountability Act is to provide relief to veterans who are mistakenly charged copayments for hospital care, medical services, or medications due to errors made by the Department of Veterans Affairs (VA). The act aims to ensure that veterans are not penalized financially when the VA fails to notify them about payment requirements in a timely manner. Key provisions of the act include the authority for the Secretary of Veterans Affairs to waive copayment requirements for certain veterans.