Ind. Code § 25-28.5-2-6

Sec. 6. Any plumbing contractor who is licensed or renews a license under this article after December 31, 1987, and upon whom personal service cannot be made with reasonable diligence shall be considered to have appointed the commission as the plumbing contractor's agent for service of process for purposes of actions filed under section 4 of this chapter for recovery from the plumbers recovery fund. Service of process under this section shall be made as nearly as practicable in the manner prescribed by the Indiana Rules of Trial Procedure for service on corporations.