Effective July 1, it is mandatory to link Aadhaar number with permanent account number (PAN). Also Aadhaar number is required for applying for new PAN number. This is implemented to check tax evasion through the use of multiple PAN cards.
If the citizens do not link Aadhaar and PAN by July 1, then their PAN card will become invalid.
Aadhaar card can now be linked online by going the following url: http://www.incometaxindiaefiling.gov.in