I know they can take your taxes but I don't know if they can only take a percentage or the whole thing. I let them take our state taxes instead of having dh fill out the paperwork to have the money sent to him. What a BIG mistake. No one could track where the money was applied, to what loan. I finally got it figured out but it took months because no one knew anything.
I would imagine if you're getting an inheritance and you've defaulted to the point where they're taking your state or federal tax returns, then if they find out about your inheritance, they'll take that too. If, however, you make an arrangement with them to make monthly payments, they won't do that. I almost had our fed tax refund taken until I made an rehab arrangement. Now my student loans are set to get out of default and, as I've been told, they'll wipe away all past due notices and it'll be like I've never defaulted. Those are basically my only negs so hello high FICO when that happens!