Stacking is not a metaphor. A single imported product can owe the MFN base duty, a Section 301 additional duty tied to an earlier trade action, and a further surcharge under another authority, each created by a different instrument and each tracked separately by CBP. The entry summary reflects that structure faithfully: separate lines, separate headings, separate amounts, which is why the document rewards line by line reading.
Refund and relief programmes respect the same boundaries. When a court ruling or an administrative programme addresses one authority, it reaches the lines assessed under that authority and not the others. An importer who works from the total duties paid line will overstate what any single programme can return, and will argue with their own broker about numbers that were never in dispute.
Start with the Chapters 1 to 97 line for each product: its ten digit classification and the Column 1 rate applied. Then read the Chapter 99 lines attached to the same entry line; the 9903 headings identify the trade remedy layer, and broker summaries or ACE data can map each heading to its authority and rate. Check the stack against what you expected for that origin and product before the entry liquidates, while correction is still cheap.
Discrepancies are common enough to justify the habit. A product that moved lists, an exclusion that expired, a supplier who changed the origin of a component: each can leave a Chapter 99 line that should not be there, or remove one that should. The entry summary is the last place the error is visible in a single document. After liquidation, the same discovery starts a protest clock conversation instead.
The paper summary your broker sends is a view. ACE holds the entry data, the liquidation status, and the line detail in the form CBP itself uses, and importer access to ACE reports turns duty review from a favour into a routine. Pull entries by period, sort by Chapter 99 duty paid, and the shipments carrying unusual stacks rise to the top of the pile, which is where a small team's review time should go.
Reconcile ACE against your landed cost records quarterly. Duties booked in the accounting system often arrive as one blended figure per shipment, which quietly erases the authority split the 7501 preserved. Keeping the split in your own records is what makes a refund claim, an exclusion filing, or a sourcing shift analysable in hours rather than reconstructable in weeks.
The skill here is small and transferable: given any entry summary, name each layer, its authority, its rate, and the instrument that created it. Anyone on the operations team who can do that can also spot the week a rate changed, a list was amended, or a broker applied last quarter's stack to this quarter's goods. Errors in trade remedy lines are rarely exotic. They are last season's truth applied one season too long.
Keep a one page stack sheet per product family, updated when an authority changes, and file it with the classification worksheet. When a broker, a supplier, or a colleague asks why this shipment carries three duty lines, the sheet answers in the entry's own language.
Keep reading: Entry Type 86 after de minimis: what the filing still does and what it no longer saves, The customs power of attorney: the document every importer signs and nobody rereads.
On separate Chapter 99 lines, in the 9903 heading series, attached to the product's entry line. The base classification and its MFN rate sit on the Chapters 1 to 97 line. Each additional duty authority gets its own Chapter 99 line and amount, which is what makes it possible to isolate what one authority cost on a given shipment.
Because it blends every layer, base duty plus each trade remedy, into one number. A refund programme, exclusion, or protest usually reaches only the layer imposed under one authority. Working from the total overstates the amount in play and hides which line actually needs correcting or claiming.
Use ACE. Importer accounts can pull entry and liquidation data directly, including line detail, so you can sort entries by Chapter 99 duty paid and review the unusual ones first. Brokers remain essential for filing, but the review itself does not need to wait for a monthly report.
Check the entry's liquidation status first. Before liquidation, a post summary correction can fix the line. After liquidation, the route is a protest within 180 days. Either way, document what the correct heading and rate should be, with the authority that imposes it, before you file anything.