Ind. Code § 4-10-11-2
In all accounts rendered for traveling expenses, receipted bills for each item, except railroad fare, shall be submitted. However, the budget agency, in cooperation with the department of administration, is authorized to fix per diem or per diems in lieu of traveling expenses, other than transportation, in such amounts as they deem proper and equitable but in no case shall such per diem exceed the amount established in the appropriation act. When per diem is fixed receipted bills for each item are not necessary. Per diem when fixed may include meals, lodging, and all other traveling expenses except transportation. It will be sufficient in items covering railroad fare to verify same, if advisable, by referring to published tariff rates, and auto transportation shall be at the rate not to exceed the rate provided in the appropriation act. Constructive charges shall be eliminated from all vouchers, and under no circumstances shall the appropriation of the succeeding fiscal year be anticipated by predecessor.
IC 4-10-11-2