when is the air filter get changed

[KiaDxb]

the air filter was not changed since i had bought this car a year back and is working good

when should i be getting it changed

???

[KiaDxb]

Its not necessary to change air filter everytime. First it has life of 30k -40k kms easy, Second it also depend on visual condition if its not black or choked completely you can use it by air gun pressure cleaning.