Permanent Account Number or PAN, as it is commonly called, is a means of identifying various taxpayers in the country. PAN is a unique identification number assigned to Indians, mostly to those who pay tax. The PAN system of identification is a computer-based system that assigns unique identification number to every Indian tax paying entity. Through this method, all tax related information for a person is recorded against a single PAN number which acts as the primary key for storage of information. This is shared across the country and hence no two people on tax paying entities can have the same PAN.
The idea behind PAN is similar to the Social Security Number or SSN used in the United States. SSN in the US is a unique nine-digit number issued to all citizens of the US, permanent and temporary both. Although, the primary aim for SSN creation was to track individuals for social security purposes, it has now become a primary identification number for taxation processes.
Any PAN issued is valid for the entire lifetime of the PAN holder. This is so majorly because PAN is unaffected by any change of address of the PAN cardholder