Annual NOC for foreign shipping: jurisdictional NOC and CA certificate streamline PCC, voyage returns, and assessments. Section 172 requires voyage returns and that port clearance follow payment or satisfactory tax arrangements. For FSCs entitled to full DTAA relief, the jurisdictional AO may issue an annual NOC listing owned, chartered and pooled vessels; that annual NOC shall, in single-carrier voyages, substitute for voyage NOC and be accepted by Customs for PCC. Where multiple DTAA-eligible FSCs supply cargo, a CA certificate plus copies of annual NOCs shall be filed instead of voyage NOCs. Otherwise a voyage NOC from the Port AO remains necessary. Port AOs must honor annual NOCs in voyage assessments or forward details to the AO issuing the annual NOC when annual assessment is elected.