Indiana Code Title 31. Family Law and Juvenile Law § 31-16-12-14

Sec. 14. (a) Except as otherwise provided in subsection (b), in any subsequent child support enforcement action between the parties, upon sufficient showing that diligent effort has been made to ascertain the location of the party by a prosecuting attorney, private attorney, or private entity operating under an agreement or contract described in IC 31-25-4-13.1, the court or administrative agency with jurisdiction shall deem state due process requirements for notice and service of process to be met with respect to the party required to provide notice, upon mailing of written notice to the other party at the most recent residential or employer address that is filed with the clerk or state central collection unit.

(b) IC 34-47-4 applies to service of an order directing an obligor to appear in a contempt proceeding.