Ind. Code § 22-4-11-4
If the commissioner finds that any employer has failed to file any payroll report or has filed a report which the commissioner finds incorrect or insufficient, the commissioner shall make an estimate of the information required from the employer on the basis of the best evidence reasonably available to the commissioner at the time and notify the employer. Unless the employer files the report or a corrected or sufficient report, as the case may be, within fifteen (15) days after the notice is sent by the department, the commissioner shall compute the employer's rate of contribution on the basis of the estimates, and the rate determined in this manner shall be subject to increase or decrease on the basis of subsequently ascertained and verified information. The estimated amount of contribution is considered prima facie correct.
IC 22-4-11-4