Originally Posted by Keyser

both the home & external affairs ministry will know exactly whether you are living in india or abroad....

Originally Posted by anirudh666

NRIs would use the same passport to travel to\from India that they entered for their GEP verification. There are electronic records of entry\exit, and almost all Indian passports these days are machine readable, so keeping track is easy.

Finance ministry would have records of income tax, NRE\NRO accounts etc. For NRE\NRO accounts, you do need to keep your latest passport on file with the bank.

With all these records, it would be easy to figure out who lives in India and who doesn't.