Notwithstanding any other provision of law, including section
6103, the head of any other agency, department, or instrumentality shall, upon receiving a written request from the Commissioner of Social Security in connection with this section, cause a search to be made of the files and records maintained by such agency, department, or instrumentality with a view to determining whether the information requested is contained in such files or records. The Commissioner shall be advised whether the search disclosed the information requested, and, if so, such information shall be promptly transmitted to the Commissioner, except that if the disclosure of any requested information would contravene national policy or security interests of the United States, or the confidentiality of census data, the information shall not be transmitted and the Commissioner shall be so advised.