According to the information written by Robert Stang in "Global Trade" Magazine, The US Customs posted CSMS # 43528998 (July 31, 2020), reminding traders that in accordance with the change in the  Post Summary Correction (“PSC”)  entered into the Federal Register on August 14, 2019 (84 FR 40430), the MPC filing deadline is extended in cases where the importer requests an extension of the liquidation deadline in accordance with 19 CFR 159.12.

Under this amended procedure, once an extension of the liquidation period has been granted to the importer, the PSC can be sent to the CBP no later than 15 days before the planned liquidation date in accordance with the extension of the liquidation period.

In accordance with the amended procedure, the PSC must be sent to the CBP within 300 days from the date of entry or no later than 15 days before the planned date of liquidation, whichever of these dates is earlier, with the exception of situations related to  extension of the liquidation period, and in this case the PSC must be sent to the CBP no later than 15 days before the planned extended liquidation date.

This change was made to increase the period within which the applicant must submit a PSC in situations related to a request for an extension of the liquidation period.

It is important to note that it may have particular application in situations where the importer obtains an extension of the liquidation period in order to retain his right to a refund in the event that the importer requests an extension of the liquidation period to satisfy a request for an exemption from section 301 or to extend the duration of the duty. 

In these cases if the duty exclusion request or the exclusion extension request is granted, then if the request for elimination of the import is also granted, the importer is given additional time to submit the PSC to Customs and receive a refund.

Of course, if the importer misses the deadline for filing a PSC in order to receive a refund, it is also possible to receive refund by filing a protest within 180 days from the date of liquidation.