The rules for “15-year”1 installment payment of federal estate tax2 require that the value of an “interest in a closely held business” exceeds 35 percent of the adjusted gross estate.3 The statute specifies that an interest in a closely held business means an interest as a proprietor in a trade or business carried on by a proprietorship, an interest as a partner in a partnership carrying on a trade or business or stock in a corporation carrying on a trade or business.4 However, there is no statutory guidance on the circumstances in which ownership of real property is deemed to be a trade or business. This has long been a matter of concern in farm and ranch estate (and business) planning because of the almost dominant role played by real estate in farm and ranch operations.