The Ministry of External Affairs, which issues passports, has made it easier for those seeking changes in date of birth in existing passports by further simplifying services.
With these changes, now one can submit digitally signed marriage and birth certificates as valid proofs of marriage and birth respectively.

joegoauk-pointofview
The revised guidelines allow the passport issuing authorities (PIAs) to consider such requests irrespective of the period that would have lapsed after the issue of the passport.
Changing the date of birth on a passport has remained a lengthy and cumbersome process. The request for change has to be made within five years of issuance of passport.
Also See

In India multiple agencies can issue birth certificates and it often leads to discrepancies.

indiatoday
If the PIA is satisfied with the claim based on documents submitted by the applicant, then passports with revised date of birth can be issued by the authorities concerned.
The ministry is also considering further simplifying the documentation process necessary for issuing passports in a timely, transparent, more accessible, reliable manner and through streamlined processes.

thelogicalindian
MEA officials said the process of issuance of passports has been made foolproof and under the new system there was no scope for anti-national elements to obtain passport.