55 Pa. Code § 149.24 – Procedures.

(a) Establishing citizenship. The statement of the client that the client is a citizen of the United States will be acceptable verification unless there is other information which indicates the contrary. Once United States citizenship is established, it will not be necessary to verify this item again.
(b) Establishing alien status. The procedures for establishing alien status will be as follows:
1. (1) The status of an alien will be established when the individual presents a current alien registration card or other written evidence from the United States Department of Immigration and Naturalization indicating that the client is legally residing in the country and not for a temporary purpose.
2. (2) If documentation is not immediately available, the statement of the client that he is lawfully residing in the country will be accepted, pending verification with the Federal Immigration Authorities. The offices of the two Immigration and Naturalization Services in this Commonwealth are as follows:
  United States Immigration and Naturalization Services
  Pittsburgh Office 2130 Federal Building 1000 Liberty Avenue Pittsburgh, Pennsylvania 15222Philadelphia Office 601 Market Street Room 1321 Philadelphia, Pennsylvania 19106
3. (3) Once alien status has been verified, it will not be necessary to reverify this item at a redetermination, except in questionable cases.