A post summary correction fixes errors before liquidation, a protest challenges CBP after it. Using the wrong tool can forfeit your remedy entirely.
Importers reach for these remedies interchangeably and they are not. A post summary correction, or PSC, is how you tell CBP the entry summary contains an error while the entry is still open. A protest is a formal legal challenge to a CBP decision, filed after liquidation, when the agency has made its determination and you dispute it. One is a correction; the other is an appeal.
Liquidation is the dividing line, the moment CBP finalizes the entry's duty assessment. Before it, the PSC window is open and comparatively painless. After it, the PSC door mostly closes and the protest clock starts running. Every entry on your calendar is marching toward that line whether you are watching it or not.
PSCs handle the everyday errors of importing: a transposed value, the wrong quantity, a classification you caught on review, an origin or preference claim that needs adjusting. Filed through your broker in ACE, a PSC can raise or lower duties owed, and it is the expected route for good faith mistakes discovered in your own post entry audits.
The limits matter. A PSC generally must arrive before liquidation, and certain changes, like some preference program claims, follow their own rules and deadlines. Discovering a systematic error across fifty entries means fifty corrections inside fifty windows. That is why importers who audit early, within weeks of entry, keep their options cheap.
A protest under 19 USC 1514 challenges CBP's call: a classification the agency imposed, a valuation decision, an exclusion denial, a liquidation you believe was wrong. It must be filed within 180 days of liquidation, it must state the grounds specifically, and it creates the record you would need if the dispute ever reaches the Court of International Trade.
Protests are slower and more formal, and they are decided by CBP first, which surprises importers who expect a neutral referee. Denial is common enough that a well built protest is written for two audiences from the start: the reviewing officer today and the court tomorrow.
The operational fix is a liquidation watch. Track entry dates, expected liquidation dates, and audit findings in one place, with alerts at ninety and thirty days before liquidation for any entry with a known issue. Pair that with a standing post entry audit cadence, monthly for high volume importers, so errors surface while PSCs are still possible.
And know when to escalate. A one off data error is a PSC and a process fix. A recurring classification dispute with real money across many entries is protest strategy and possibly counsel, because the outcome sets your treatment for every future shipment of that product. Choosing the right remedy is legal hygiene, but choosing it in time is operations.
Generally before the entry liquidates. Once CBP liquidates the entry, the PSC route closes for most changes and remedies shift to protests or other specific procedures.
180 days from the date of liquidation. The deadline is statutory, and late protests are denied as untimely regardless of how strong the underlying claim is.
Not at the same time for the same entry. Before liquidation you correct; after liquidation you challenge. Filing strategy depends on where the entry sits relative to liquidation.
CBP reviews its own decision first. If the protest is denied, the importer can take the dispute to the Court of International Trade, which is why protests should be documented like legal filings.