Is there a VA rule that covers a veteran receiving TDIU for many years and has no changes in mental or physical status that qualified them for a TDIU is guaranteed that their benefit of 100% will not be taken away? I remember reading something about a 20 year rule but with all the changes not sure what still stands.
No, there is no absolute rule that says a benefit may not ever be taken away. There are some protections built in at the point where a benefit has been held for 20 uninterrupted years but even then, if VA has reason to, they can and will open a file for investigation. The word permanent at VA doesn't mean permanent. Using the word permanent only denotes that certain expanded benefits are available to that beneficiary...it doesn't mean the benefit can't ever be modified.