Indiana Code Title 6. Taxation § 6-4.1-9-1.5

Sec. 1.5. If inheritance tax is imposed because a petition is filed under IC 6-4.1-7-6, the inheritance tax so imposed is, notwithstanding section 1 of this chapter, not due until thirty (30) days after notice of the final determination of federal estate tax is received by a person liable for paying the inheritance tax.  If any inheritance tax so imposed is not paid on or before the due date, the person liable for paying the tax shall pay interest on the delinquent tax at the rate of six percent (6%) per year from the due date until the tax is paid.