Section 5316 of Title 31 requires any person who transports or has someone else transport United States currency or other monetary instruments in excess of $10,000 into or out of the United States, or who receives such monetary instruments in the United States from abroad, to report the transaction. This report is made on Form 4790 ("Report of International Transportation of Currency or Monetary Instruments," commonly known as a CMIR), which must be filed with the United States Customs Service at the time of entry into the United States or at the time of departure, mailing, or shipping from the United States.
Enforcement of the export/import reporting requirements is strengthened by two additional provisions: (1) 31 U.S.C. § 5317(a) authorizes the Customs Service to apply for a search warrant to search for and seize monetary instruments which are not reported; and (2) 31 U.S.C. § 5317(c) permits the United States to seek the forfeiture of monetary instruments for which a CMIR has not been filed, or for which the CMIR contains a material omission or misstatement, as well as any property involved in the offense.
The implementing regulations for § 5316 are found at 31 C.F.R. § 103.23. It is important that prosecutors, in considering a CMIR-related prosecution or forfeiture, consult the implementing regulations in effect during the period that the violations under consideration occurred.