As per the Patents Act, the term of a Patent of addition filed on 13.04.2012 (granted on 15.01.2015)…

Under section 55(1) of the Patents Act, 1970, a patent of addition is granted "for a term equal to that of the patent for the main invention, or so much thereof as has not expired". Its own filing or grant date does not start a fresh term.

The main patent runs for twenty years from its filing date of 15.07.2008 (section 53(1)), so the patent of addition also ends on 15.07.2028. Dates counted from the addition's filing or grant, or from the main patent's grant, are wrong.