evidence: If such assets are held and passed on after death, the value is adjusted to the fair market value at the time of the inheritance under what’s called stepped-up basis. That means all of the gains earned up until the inheritance would never be taxed. Erica York, a senior economist and research manager at the Tax Foundation, told us when we wrote about Biden’s claim in February that one issue with wealthy families is that they could "purchase assets that appreciate (increase in value), and then borrow money against their assets to consume their wealth without paying tax." Then, the assets can be passed on to heirs through inheritance and the gains up until that point aren’t taxed. She referred to the strategy as "buy, borrow, die." Biden aims to change that through a billionaire minimum tax to ensure those worth over $100 million pay at least 20% in federal income taxes, as calculated on both standard income and unrealized gains combined.