The Under Secretary also provided policy guidance over the Internal Revenue Service's Criminal Investigation Division.

[6] The U.S. Secret Service and the Federal Law Enforcement Training Center are now within the Department of Homeland Security.

[9] However, under the Homeland Security Act of 2002[10] Custom Service's "revenue functions" were retained by Treasury.

This includes, among others, Customs duties, enforcing trade agreements, and counterfeit trademark detection and seizure.

[11] Former under secretaries include Jimmy Gurule,[4] James Johnson,[12] Raymond Kelly,[13] Ronald Noble,[14] Stuart A. Levey, and David Cohen.