A post summary correction, filed in ACE as a PSC, lets an importer amend an entry summary after filing but before liquidation. Classification, value, quantity, and Chapter 99 reporting lines can all move on a PSC. Once the entry liquidates, that door closes and the only routes left are a protest under 19 USC 1514 or, where a material error is involved, a prior disclosure. The difference is not paperwork style. It is whether the correction is routine or adversarial.
What a PSC can actually change
A PSC can correct the HTSUS line, the entered value, the country of origin, and the special program indicator, provided the entry has not liquidated and is not under a restriction that blocks amendment. Duty is recalculated on the corrected figures and CBP either bills the difference or refunds it through the normal process. What a PSC cannot do is resurrect a preference claim that was never supportable, change the importer of record to a different party, or rewrite history on an entry that CBP has already flagged for review. Brokers file PSCs daily. The failures are rarely technical. They are timing failures, where the error is found in month thirteen and liquidation happened in month eleven.
Finding errors while the window is open
The useful habit is a scheduled entry review, not a panic review. Pull a report of entries by HTSUS line and value band, compare it against the commercial invoices and the classification worksheet, and look for the patterns that repeat: the same part entered under two codes, a value that excludes an assist that should be dutiable, a Chapter 99 line missing on a Section 301 list product. One PSC fixes one entry. A pattern found early fixes the forty entries behind it that have not liquidated yet, and it changes the instruction the broker works from next month.
PSC, protest, or prior disclosure
Choose the instrument by status, not by preference. Entry open and not liquidated: PSC. Entry liquidated and the issue is classification, value, or a preference claim CBP denied: protest within 180 days of liquidation. Entry in any status where the error is a material false statement, a wrong origin claim, an undervaluation that was not a judgement call: talk to counsel about a prior disclosure before CBP finds it first, because the disclosure is what limits the penalty exposure. Mixing these up wastes the one window each instrument gives you.
The record a PSC needs
File the correction with the evidence attached in the entry packet: the invoice that supports the corrected value, the product description or ruling that supports the corrected code, and a short note stating what was wrong in the original filing. CBP reviews PSCs, and a correction with no support reads as a second guess rather than a fix. Keep the original and corrected summaries together by entry number. If the entry is later audited, that pair of documents, plus the reason for the change, is the whole defence.
Keep reading
Related guides on this site: Liquidation Notices: What the Extension Clock Actually Means ISF Filing Errors: The Mistakes That Draw Liquidated Damages Answers for teams shipping Shopify orders across borders.
Frequently asked questions
When is the deadline for a post summary correction?
Before liquidation of the entry. Liquidation commonly occurs about a year after entry but can be extended or suspended, so the ACE status of the specific entry controls, not the calendar.
Does a PSC change the duty owed?
Yes. Duty is recalculated on the corrected classification, value, and program claims. CBP will bill any increase or process a refund for a decrease through the entry's normal liquidation path.
Can a PSC fix a Section 301 reporting line?
Yes, while the entry is unliquidated a PSC can add or correct the Chapter 99 reporting line that carries the Section 301 action, provided the underlying HTSUS classification supports it.