In order to be compliant with Automated Clearing House (ACH) and Office of Foreign Assets Control (OFAC) rules, any transaction where the "ultimate" source or destination of funds is outside of the United States, should be coded as an International ACH Transaction (IAT).  This ACH format contains several additional addenda records to allow the ACH transaction to carry necessary information to appropriately identify the source and destination of the funds for sanctions screening and Bank Secrecy Act (BSA) compliance purposes.  The source and destination must be at the very "ends" of the transaction flow - where the funds are coming from, and where the funds are going to. 

IAT transactions include the domestic leg of international transactions, (i.e. a transaction between a US bank and another US bank, where the source of funds is from a foreign source or where the funds are ultimately delivered outside the US (regardless of how those funds get there - Check, Wire, Intercompany Settlement, etc)). 

There are a variety of resources available including the Nacha International ACH Transactions solutions center:  https://www.nacha.org/content/international-ach-transactions-solutions-center 

This IAT file format guide is to be used as a supplemental tool to the format listed in the NACHA rules. Organizations can use this to help make changes in their system to prepare for the IAT format; however, it is important to note that the actual content of the fields will vary depending on the destination and type of transaction being sent. 

Note: The IAT ACH transfer object contains all the information needed to transfer money including bank account information, amount, and dates. It also provides the transfer’s current workflow status.  We keep the core body of the ACH transfer object the same, and add an IAT specific details object. 

Attributes

IAT Details Object Attributes
 

As defined by the NACHA guidelines: 

• Mandatory for ACH Operator Processing: 
  A “mandatory” field is necessary to ensure the proper routing and/or posting of an ACH entry. 
  Any “mandatory” field not meeting required data specifications, as defined within Appendix Two (Specifications for Data Acceptance by ACH Operators) will cause the ACH operator to pend or reject the file, batch, or entry. A file, batch, or entry placed in a pending status by the ACH operator will await action to be released or rejected, based on instructions provided by the sending point. The ACH operator will report to the ODFI or its sending point any file, batch, or entry placed in a pending status or rejected by the ACH operator. A rejected entry will be returned to the ODFI or its sending point by the ACH operator.