If you’re planning your estate, or you’ve recently inherited assets, you may be unsure of the “cost” (or “basis”) for tax purposes. Generaly, there is a stepped-up basis of inherited property. Fair market value rules Under the fair market value basis rules (also known as the “step-up and step-down” rules), an heir receives a basis in inherited property equal to its date-of-death value. So, for example, if your grandfather bought ABC Corp. stock in 1935 for $500 and it’s worth $5 million at his death, the basis is stepped up to $5 million in the hands of your grandfather’s heirs — and all of that gain escapes federal income tax forever. The fair market value basis rules apply to inherited property that’s includible in the deceased’s gross estate,...