If  the law changes everyone has to pay capital gains tax on the increased value of inherited assets, doing taxes will be a nightmare for those who did not plan for that. How do I find out what my father  paid for stock bought over many years through a workplace plan when it comes to me?  With no proof I'd probably have to assume a basis of zero and pay capital gains on the full amount.  Wealthy families know this is coming and keep records. Someone with a net worth of $100,000 probably didn't.