So long as any adoptive parent is receiving support pursuant to RCW
26.33.320 and *
74.13.100 through
74.13.145 he or she shall, upon request, file with the secretary a copy of his or her federal income tax return. Such return and any information thereon shall be marked by the secretary "confidential", shall be used by the secretary solely for the purposes of RCW
26.33.320 and *
74.13.100 through
74.13.145, and shall not be revealed to any other person, institution or agency, public or private, including agencies of the United States government, other than a superior court, judge or commissioner before whom a petition for adoption of a child being supported or to be supported pursuant to RCW
26.33.320 and *
74.13.100 through
74.13.145 is then pending.
In carrying on the review process authorized by RCW
26.33.320 and *
74.13.100 through
74.13.145 the secretary may require the adoptive parent or parents to disclose such additional financial information, not privileged, as may enable him or her to make determinations and adjustments in support to the end that the purposes and policies of this state expressed in *RCW
74.13.100 may be carried out, provided that no adoptive parent or parents shall be obliged, by virtue of this section, to sign any agreement or other writing waiving any constitutional right or privilege nor to admit to his or her home any agent, employee, or official of any department of this state, or of the United States government.
Such information shall be marked "confidential" by the secretary, shall be used by him or her solely for the purposes of RCW
26.33.320 and *
74.13.100 through
74.13.145, and shall not be revealed to any other person, institution, or agency, public or private, including agencies of the United States government other than a superior court judge or commission before whom a petition for adoption of a child being supported or to be supported pursuant to RCW
26.33.320 and *
74.13.100 through
74.13.145 is then pending.