NRI applying for PAN (Permanent Account Number) is as simple as applying PAN for any Resident Indian. An NRI who is an Indian citizen can make the application for PAN in the same form 49A used by any resident Indian, but the individuals who is not an Indian citizen has to apply it through form 49AA. Persons of Indian origin (PIOs) and overseas citizens of India (OCIs) have to fill in form 49AA, too. Such applications can either be made offline by downloading the forms from www.incometaxindia.gov.in or online through NSDL site
Update December 28, 2013; New PAN application form 49A, 49AA Notified: Documents required to apply PAN Card
As the application can be filed online, but a signed copy of the acknowledgement along with photographs and proof of identification and proof of address has to be submitted manually also. You need to submit two passport-size photographs one of which should be signed across. Along with the application, certain documents are required to be submitted as proof of identity and proof of address.
In case of form 49A, the documents accepted are proof of identity including school leaving certificate, depository account statement, bank account statement, passport, driving licence and voter identity card, and is to be self attested. For proof of address, telephone bill, electricity bill, depository account statement, passport, driving licence and voter identity card which are self attested, or copy of bank account statement in the country of residence or copy of non-resident external (NRE) bank account statement duly attested by the bank manager are accepted.
In case of form 49AA, the documents required for proof of identity include a copy of passport, copy of PIO card issued by the Indian government, copy of OCI card issued by the Indian government, copy of other national or citizenship identification number, taxpayer identification number, duly attested by the Indian embassy/consulate/high commission in the country where the applicant is located. For proof of address, any of the documents listed above or a copy of the bank account statement in the country of residence or a copy of NRE bank statement in India, duly attested by the bank manager, is also accepted.