I have a question about if necessary
Hello
I have a question
if necessary is used instead of if it is necessary
what does it refer to?
does it have a meaning?
Thank u for your advice

Question

I have a question about if necessary
Hello 
I have a question
if necessary is used instead of if it is necessary
what does it refer to?
does it have a meaning?
Thank u for your advice

Answer

They mean the same thing. "If necessary" is just a shortened version and sounds a little cleaner. Both are correct though.

Answer

The meaning is pretty much the same thing for both.