A permanent account number (PAN) is a ten-character alphanumeric identifier, issued in the form of a laminated "PAN card", by the Indian Income Tax Department, to any "person" who applies for it or to whom the department allots the number without an application. It can also be obtained in the form of a PDF file. It is also issued to foreign nationals (such as investors) subject to a valid visa, and hence a PAN card is not acceptable as proof of Indian citizenship. A PAN is necessary for filing income tax returns.