Ind. Code § 6-4.1-9-1
(b) If an unavoidable delay, such as necessary litigation, prevents a determination of the amount of inheritance tax due, the department of state revenue may reduce the rate of interest imposed under this section, for the time period beginning on the date of the decedent's death and ending when the cause of delay is removed, to six percent (6%) per year.
As added by Acts 1976, P.L.18, SEC.1. Amended by P.L.252-2001, SEC.6; P.L.190-2016, SEC.24; P.L.79-2017, SEC.40.