If a decision involving services is reversed, normally the service will be provided from the time of the decision instead of retroactively; however, if by reason of having been excluded from the services, the client has been required to expend funds, or has incurred unpaid bills for services erroneously reduced or denied, then he or she or the provider, if appropriate, would be entitled to the reimbursement of expenditures retroactively.
40 Tex. Admin. Code § 730.1402