The definitions of "responding State" and "responding tribunal" in Subsections (18) and (19) accommodate the direct filing of a petition under UIFSA without the intervention of an initiating tribunal. Both definitions acknowledge the possibility that there may be a responding State and a responding tribunal in a situation where there is no initiating State or initiating tribunal.

Subsection (21) no longer requires reciprocity between the several states, formerly a cornerstone of RURESA and URESA. Public policy favoring enforcement of child support orders is sufficiently strong to warrant waiving any quid pro quo requirement between U.S. jurisdictions. This was true even before the issue was mooted by the enactment of UIFSA by all states by 1998.

The 1996 amendment to Subsection (21) clarified the position that UIFSA, like RURESA before it, does not waive reciprocity in the international context. A major amendment to the text of Subsection (21) was made in 2001 to make clear that a foreign country or political subdivision is defined as a "State" under the Act in three situations. First, a declaration by the U.S. State Department that a foreign jurisdiction is a reciprocating country or political subdivision is controlling for all states. Second, in the absence of such a declaration, each of the several states can make an arrangement with a foreign country or political subdivision for reciprocal enforcement of child support. Finally, a finding may be made that a foreign jurisdiction has a law or procedure substantially similar to UIFSA. That is, a tribunal may consider whether the foreign jurisdiction also has laws and procedures that allow for a U.S. order to be recognized in that foreign jurisdiction independent of a formal reciprocity agreement. The inclusion of foreign political subdivisions is necessary because in some countries the central government will not or cannot bind the subdivisions. For example, reciprocal arrangements with Canada are made on the province level and not with the Canadian federal government.

Although the vast bulk of child support establishment, enforcement, and modification in the United States is performed by the state IV-D agencies, see Part IV-D, SOCIAL SECURITY ACT, 42 U.S.C. Section 651 et seq., Subsection (22) defines the term "support enforcement agency" to include not only those entities, but also any other state or local governmental entities charged with establishing or enforcing support. The 2001 amendment simply adds another key task to the list of powers, that is,