Release of goods is the start of an entry's life, not the end. Customs liquidates the entry later, finally determining the classification, value, and duty owed, and that liquidation is the legally final word unless it is protested within the window, generally 180 days. Extensions and suspensions can push liquidation years out for some entries, notably where antidumping or countervailing duties are involved, which is why a container sold and forgotten can still produce a duty bill with interest.
At entry, the importer deposits estimated duties. Estimated is the operative word. If CBP's final view differs, because a classification was adjusted, a value was corrected, a preference claim was denied, or a rate changed under a suspension of liquidation, the difference is billed or refunded at liquidation. Finance teams that close the books on the estimated figure are not wrong to use it. They are wrong to treat it as settled, especially in categories where liquidation is routinely suspended.
AD and CVD entries are the extreme case: cash deposits at entry are estimates against rates that can be recalculated in administrative reviews concluding years later, and the final liability follows the review, not the deposit. An importer in a covered category who does not reserve for that spread is running an unpriced liability through the middle of the business.
The protest window, the mechanism for challenging CBP's decisions on classification, value, and preference, opens at liquidation and runs 180 days from it. That timing surprises importers twice: first, because a liquidation they never noticed can close the window on a claim worth real money, and second, because refunds and bills alike arrive by the liquidation notice, which someone in the organisation has to actually read. Assign liquidation notices an owner, a broker report, a calendar, the way any other legal deadline gets owned.
Liquidation can also be reliquidated in limited circumstances, and CBP can correct certain errors through its own mechanisms, but none of that rescues a protest deadline slept through. The system rewards importers who watch the docket and gives the others finality instead, which is its own kind of answer.
Reconcile entries to liquidations on a cycle: which entries remain unliquidated, how old are they, which categories are suspended, and what is the exposure if they liquidate adversely. Hold the estimated duty as a liability until liquidation for the lines where adjustment is plausible, and release it when liquidation confirms it, which converts a surprise process into a boring one. Boring is the goal. Customs exposure should never be the most exciting line in a quarter.
Confirm the status of your significant open entries with your broker regularly. A liquidation report is a standard ask, and an importer who has never seen one is not being protected by the silence. They are being exposed by it.
Related reading: How do you audit your customs broker's entries before CBP does?, What happens when CBP rejects your entry summary?.
CBP generally aims to liquidate within a year of entry, and entries not liquidated in time can be deemed liquidated at the rate asserted at entry, subject to the rules and exceptions. Extensions can add up to a further period, and suspensions, common with AD and CVD, can hold an entry open for years. The range is why status, not assumption, should drive your reserves.
Release lets the goods enter commerce. Liquidation finally settles the money. Between them, the entry is provisional in every way that matters to your accounts, which is why a warehouse full of sold goods can still carry unsettled duty liability behind it.
If liquidation produces a refund, CBP processes it, but importers who believe the liquidation itself is wrong, wrong rate, wrong classification, wrong preference treatment, must act inside the protest window to change it. Silence accepts the computation, favourable or not, and closes most routes to revisit it.
Usually because a court order or an administrative process, most often an antidumping or countervailing duty review, prevents final assessment until the underlying rates are settled. Suspension is not an error and it is not forgiveness. It is a pause, and the bill at the end of it is computed on the final rates, with interest.