The Mexican government has stepped up efforts to prevent the undervaluation of imported goods and is now actively using reference prices for that purpose. This policy currently applies to textile, apparel and footwear items. Shipments of affected goods not accompanied by documentation sufficient to confirm the correct value could be seized and/or subject to penalties. Although this mechanism was created in December 2011 after the elimination of the transition duties that were in place on a range of mainland Chinese goods, the number of associated seizures has increased recently.

Mexico's Tax Administration Service (Servicio de Administracin Tributaria, or SAT) has determined that in 2011 68 percent of textile, apparel and footwear items imported from mainland China, Hong Kong, Taiwan and other suppliers were entered at prices lower than the cost of raw materials used in their production. To discourage this practice, SAT has implemented a programme known as "Precios de Referencia" (reference prices) with respect to 413 tariff lines for textile items and 59 tariff lines for footwear. These reference prices are determined on a computed value basis but will not be published in the Diario Oficial and importers will not have access to them. The specific tariff lines subject to reference prices have not been made publicly available either.

SAT officials have emphasised in several forums in Mexico that the reference prices are only used to analyse the risk of importers using lower values and are not used in deciding whether to reject or accept the value declared in entry summaries. However, if the merchandise is imported at a price lower than the reference price, Mexican Customs will require the importer to have a guarantee of import duties based on the reference price.

When an importer becomes aware that the price agreed with its supplier is low it must obtain the proper documents to support that price and notify the customs broker of this situation. The broker will then include in the pedimento the code "PV" (prueba de valor, or proof of value) indicating that it has the documentation to prove the transaction value and clear the shipment through customs. In this context Mexican Customs require the commercial invoice as well as the following documents.