Subsection (6) is written broadly to include an "income withholding order" based on "other legal process," as distinguished from "by order of a tribunal." Some states issue such orders administratively, which are entitled to enforcement notwithstanding the fact that no judicial or quasi-judicial process is involved. Federal law requires that, in order to be eligible for federal subsidy monies, each State must provide for income withholding "without the necessity of any application therefor, or for any further action by the court or other entity which issued such order ." 42 U.S.C. Section 666(b)(2). States have complied with this requirement in a variety of ways.

From its beginning UIFSA has permitted direct filing of an interstate proceeding in a responding State without an initial filing in an initiating tribunal. This has become the standard operating procedure for child support enforcement agencies. Thus, a petitioner in one State may seek to establish, enforce, or modify a support order in a second State by either filing in the responding state's tribunal or by directly seeking the assistance of the support enforcement agency in the second State. Although Subsections (7), (8), (18) and (19) supply definitions for "initiating and responding State" and "initiating and responding tribunal," the procedure of "initiation and response" established by the predecessor acts of URESA and RURESA has become an anachronism since the universal enactment of UIFSA.

Until the 2001 amendments, the relationship between UIFSA and the prior uniform acts was captured in the reference to URESA and RURESA as "substantially similar" acts. This phrasing in Subsections (7), (18) and (21), and repeated several times throughout the Act, has been deleted everywhere it appears to avoid confusion that might arise from appearing to incorporate statutes that have been replaced. This is not to suggest in any way that support orders issued under URESA or RURESA are not fully enforceable under UIFSA. Until valid orders issued under those laws expire of their own terms or are replaced by new UIFSA orders, the support orders themselves will continue to have vitality, see Sections 201-211, infra. In short, UIFSA is specifically designed to function with the earlier acts without conflict. Support orders issued under one of the earlier acts should be honored and enforced in every State. But, despite their common roots, neither URESA nor RURESA can be said to be "substantially similar" with regard to the continuing, exclusive jurisdiction/one-order system established in UIFSA. States are directed to accord full enforcement remedies to support orders