Merchant overtime fee requires prior request and payment before Customs officers are posted for work outside normal hours. Parties seeking Customs officers on an overtime basis must make a prior request; Customs assesses the requirement and calculates a merchant overtime fee under prescribed rates, and officers are posted only after payment. A separate fee applies if the broker, vessel, or party changes, while a single fee suffices for multiple documents handled by the same broker or multiple activities of the same importer/exporter within the same block. Custodian requests for services beyond normal hours are allowed upon payment of the merchant overtime fee.