48 C.F.R. § 32.1106 – EFT mechanisms.

(a) Domestic EFT mechanisms. The EFT clauses at 52.232-33 and 52.232-34 are designed for use with the domestic United States banking system, using United States currency, and only the specified mechanisms (U.S. Automated Clearing House, and Fedwire Transfer System) of EFT. However, the head of an agency may authorize the use of any other EFT mechanism for domestic EFT with the concurrence of the office or agency responsible for making payments.
(b) Nondomestic EFT mechanisms and other than United States currency. The Government shall provide payment by other than EFT for payments received by or on behalf of the contractor outside the United States and Puerto Rico or for contracts paid in other than United States currency. However, the head of an agency may authorize appropriate use of EFT with the concurrence of the office or agency responsible for making payments if—
1. (1) The political, financial, and communications infrastructure in a foreign country supports payment by EFT; or
2. (2) Payments of other than United States currency may be made safely.