If a defendant pleads not guilty and he is later found guilty, can the prosecution then charge him for perjury?

A defendant can not be charged with perjury for pleading not guilty. The crime of perjury is for lying under oath.

A not guilty plea is nothing more than letting the court know that you require the prosecution to prove its case. It is the states burden to prove you guilty.

No perjury in a plea. Only if you lie under oath.

No, pleading "not guilty" is very common and the most advisable way to start a case, in order to have time to explore a defense.

To be found guilty of perjury a person has to lie under oath. A plea of not guilty at the beginning of a case is just a way to allow the defendant the time to see what the evidence is against him/her and to protect constitutional rights. So if the person never takes the stand then he/she could never be charged with perjury. If he/she takes the stand and lies and it is proven that he/she lied then yes, perjury would be charged. This rarely happens.