I received a 1099-R for my military retirement pay but I am 90% disable veteran. Do I owe taxes on my entire retirement pay?

I was told at retirement that I only pay taxes on my retirement pay after I subtract my VA Disability.  So If I am 100% disabled then I don't pay taxes on 100% of my retirement check.  Is this correct and if so how do I file it on my taxes with the 1099-R?