9 C.F.R. § 130.4
(a) Services subject to hourly rate user fees. User fees for import- or export-related veterinary services listed in paragraphs (a)(1) through (18) of this section, except those services covered by flat rate user fees, will be calculated at the hourly rate found online at www.aphis.usda.gov/business-services/vs-fees, for each employee required to perform the service. The person for whom the service is provided and the person requesting the service are jointly and severally liable for payment of these user fees in accordance with §§ 130.6 and 130.7.
(b) When do I pay an additional amount for employee(s) working overtime? You must pay an additional amount if you need an APHIS employee to work on a Sunday, on a holiday, or at any time outside the normal tour of duty of that employee. Instead of paying the hourly rate user fee, you pay the rate found online at www.aphis.usda.gov/business-services/vs-fees for each employee needed to get the work done.
(Approved by the Office of Management and Budget under control numbers 0579-0015, 0579-0020, 0579-0040, and 0579-0055)