Colorado Department of Revenue
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Audit Results

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You are entitled to request and receive copies of the audit working papers, which normally include schedules that document the tests and examination procedures used in the audit. The audit working papers also include the auditor's narrative comments describing your records, explaining the purposes of the tests conducted, and interpreting the findings of those tests.


If your records are unacceptable for audit purposes, the auditor can determine your liability and may:


  • Estimate the number of gallons of gas you used based on your driving history or by comparing your operations to similar operations.
  • Use a standard of 4.0 miles per gallon of gas.
  • Not allow any claims for tax-paid fuel without supporting documentation.
  • May assess 100% Colorado fees, plus applicable interest and penalties.
  • The Internation Fuel Tax Association/Internation Registration Plan (IFTA/IRP) licensee has the burden of proving that your records and statements are correct.


Upon completion of the audit, you will be sent a Colorado IRP Audit Adjustments Statement.  If the audit resulted in additional tax due, the department will send you a billing. You have 30 days from the date of the notice to pay the amount due or to file a protest.  To protest you must notify the Colorado Motor Carrier Services in writing within 30 days of the date of this letter.  If the results of a re-examination are not in your favor, however, please be aware that no additional interest will accrue during that period.  If the audit resulted in a refund, we will issue you a check after payment of any other outstanding amounts you may owe.


We will provide a copy of the audit report to all member jurisdictions. Any member jurisdiction may choose to reexamine the audit findings. In addition, a member jurisdiction may choose to re-audit your account at its own expense, after notifying you and us of the reasonable cause for the re-audit.