In the world of modern international trade, many if not most, of the various elements of a transaction of goods manufactured may be impossible to accurately determine at the time the merchandise is imported or exported. The value of equipment used in the manufacturing of the product, the exact value of the lease of facilities that house maquiladoras in Mexico, or perhaps the exact man hours per unit of an item produced may not be known until the close of an accounting period. Because of these, and many other variables in the modern process of production, the precise and accurate value or cost of products may not be known until the final accounting has been done.

To compensate for such an accounting gap, the Automated Commercial System (ACS) Reconciliation Prototype allows importers to file entry summaries with U.S. Customs and Border Protection (CBP), using estimates based on the most reliable information available, leaving many elements outstanding for the time being. When precise and specific data has been acquired and determined, the importer can then file a reconciliation entry, supplying the final and exact information for the flagged entries in need of completion. At this point, the payment of additional duties, taxes, fees, and interest (or claim for refund) is made. The Reconciliation is processed and liquidated, and a final composite bill or refund is issued to the importer.

This allowance is especially pertinent for maquiladoras in Mexico, as maquilas cannot typically establish transaction value. This is primarily due to three factors:

(1) There is typically no official sale of merchandise or finished goods by the maquiladora to the US importer.
(2) Most maquiladoras in Mexico are paid for value added on an as-needed basis – this information does not necessarily come with a price tag stamped on the side of a crate.
(3) It is not a simple matter of comparing apples to apples, because transaction value for identical or similar merchandise cannot typically be identified.

Due to these factors, when it comes to customs reconciliation, maquiladoras in Mexico are better off using the computed value method for customs valuation, which is generally easier to document, and often results in a more favorable valuation, and thus a better reconciliation, than other methods.

Computed value is the sum of the cost of materials and processing employed in production of the imported goods, profit and general expenses usually reflected in export sales to the country of importation, and other considerations like transportation costs, loading costs, handling fees, and even insurance. Though it is a bit more complicated than other options, maquiladoras in Mexico often receive a higher refund at the time of reconciliation by opting for this method of valuation.