Tex. Health & Safety Code § 773.058

An individual who is an emergency medical services volunteer is exempt from the payment of fees under Section 773.055 if the individual does not receive compensation for providing emergency medical services. If an individual accepts compensation during the certification period, the individual shall pay to the department a prorated application fee for the duration of the certification period. In this section, "compensation" does not include reimbursement for actual expenses for medical supplies, gasoline, clothing, meals, and insurance incurred in providing emergency medical services.