Chapter 99 (specifically heading 9999) is used to record statistical estimates for low-value shipments that are not individually classified, as well as salvage and other transactions that cannot be assigned to a standard commodity code. These entries appear in trade data as accounting adjustments rather than as actual merchandise imports.

In practice, chapter 99 entries are generated by CBP and Census Bureau statistical processes, not by importers filing standard entry summaries. Importers should classify goods under the appropriate commodity chapter. If a shipment appears to have been reported under chapter 99, it typically reflects a data-aggregation convention rather than an importer's classification decision.