The PAN card is a unique identifying card with a number for taxpayers in India. The Permanent Account Number – PAN - is actually a number which will identify you to the Income-tax Authority. A computer system assigns the PAN to all Indian tax payers whether you are an individual or a company. All your tax-paying information is stored under your PAN and can be retrieved at any time using this unique number. This PAN is available to every citizen in India. A PAN is allotted to each individual or company and there is no duplication.
The Pan can be compared to the Social Security Number or SSN in the USA. The SSN is allotted to every legal resident of the USA whether citizen or not. It was chiefly used to identify people for social security benefits but today the nine-digit SSN is used in tax processes also.
Your PAN is allotted only once and will not change throughout your life. Even if you change your address your PAN is unaffected.