When and How to use Post Summary Corrections

As an importer or broker you are allowed to submit a post summary correction (PSC) for an existing ACE entry for type 01 and 03 entry summaries. These replace the existing post entry amendment (PEA) for ACE entry summaries. If a PSC is filed by someone other than the original filer, the original filer will not get a courtesy notice of liquidation via ABI but they will get an Entry Summary Status Notification message to the new filing. They will also be able to run an ABI query and view limited information on the entry summary that was corrected.

As according to US Customs:

They must be filed within 270 calendar days of the date of entry.
They cannot be filed within 20 calendar days of the scheduled liquidation date.
ACE will reject the submission if the entry summary is less than 21 days from the liquidation date.
The entry summary cannot be liquidated.
The entry summary must be in “accepted” status in CBP control.
There is no limit to the number of PSC’s that may be filed within the permitted time period as long as all filing conditions are met.
Filers are required to transmit one or more reason codes for the change.

Even though you can change a lot with PSC's, there are some data elements you can't change in a PSC and it includes the following below.

The Post Summary Correction Restrictions are:

District/port of entry
Importer of record
NAFTA reconciliation indicator
Payment type code
Live entry indicator
Periodic statement month
Location of goods
Cargo release certification request indicator including DOT, FDA and PGA grouping
Statement client branch identifier
Consolidated summary indicator
Statement client branch identifier
Any release details (release entry filer code, release entry number)