The battle over the portion of value of property owned in joint tenancy (or tenancy by the entirety) receiving a new basis at death moved a notch closer to resolution with a 1998 Tax Court case. In that decision, Hahn v. Commissioner, the Tax Court agreed with five earlier cases that a surviving spouse may be entitled to a new income tax basis in 100 percent of the date of death value of property held in joint tenancy with a predeceased spouse.