The Internal Audit program provides both an internal and external function. The internal function evaluates the needs, adequacy and effectiveness of managerial systems and controls pertaining to financial, accounting, and business activities. They review the handling of Department receipts and funds to see that they are properly protected by accurate and efficient accounting controls, and that expenditures have been made in conformance with law and good business practice. Auditors also complete special investigations requested by department management, employees, and tax payers. The external function reviews to ascertain whether or not statutory or departmental requirements are being followed relating to Consultant Engineering and Utility Relocations.

The Office of Internal Auditor provides resources and pays for the department-wide federal 'Single Audit'. This audit is required to comply with regulations governing the receipt of federal-aid highway funds. Any outside performance audits of the Department are paid for with funds from the Internal Audit program.

The Office of Internal Auditor successfully completed a Peer Review conducted by the American Association of State Highway and Transportation Officials Audit Subcommittee during 2012. This means that they are in compliance with General Accounting Office's Governmental Auditing Standards.