The same barrel of residue can carry a tax gap of over a thousand yuan depending on the route. Fuel oil, as a taxable consumer product, bears consumption tax of roughly ¥1,218/t on the domestic leg, while bitumen sits outside the levy. That one-in-one-out difference decides whether entrepot cargo is sold first and taxed later, or taxed on arrival.

The bonded-zone logic: cargo that is not actually imported for domestic sale turns over inside the zone or under adjacent customs supervision, so VAT and consumption tax defer until the moment it truly leaves the zone for home sale. For SNSUC's offshore-supply, refinery-quota structure, deferral means less in-transit tax tied up per unit of cargo and a lighter cycle.

But the deferral is not automatic; two locks hold it. First, three-document consistency—contract, invoice, and bill of lading must agree on name, quantity, and date—or customs will not treat it as genuine transshipment. Second, an SHA-256 title fingerprint placed upstream of bill issuance makes the ownership chain traceable and tamper-evident, writing where the cargo is and who owns it as machine-verifiable proof.

In practice: for every bonded-entrepot batch, attach the SHA-256 fingerprint and document hash before the bill is issued, not at export declaration. Break the three-document or fingerprint chain and the deferral lapses—back tax plus penalty can add several million yuan on a single vessel.