IFTA tax returns

How to file a return

You must submit your return even if no payment is due.

  1. Complete an International Fuel Tax Agreement Tax Return form.
    • Remember to sign and date your return.
    • When you’re done, send it to us as described in Step 2.
    Use the online system to complete a return.
    • Before you can use the online system, you’ll need to apply for access by sending us all of the following:
    • After we process your application, we’ll send you a password and instructions on how to access and use the online system.
    • Once you get your password, you can fill out your return online. The system will complete all the calculations to determine your tax liability or credit.
    • When you’re done, print a copy of the return, sign it, and send it to us as described below.
  2. Send us your completed return:
    • If you’re including a payment, mail your completed return and a check to:
      Prorate and Fuel Tax
      Department of Licensing
      PO Box 3777
      Seattle, WA 98124-3777
    • If you’re sending only your return (without a payment), mail or fax it to:
      • Mail:
        Fuel Tax Section
        Department of Licensing
        PO Box 9228
        Olympia, WA 98507-9228
      • Fax: 360.570.7839 or 360.586.9729

Interest charged on late returns

Starting July 1, 2013, interest calculation on fuel taxes owed to Washington State from your International IFTA tax return will be set annually at 2 percentage points above the underpayment rate established under the Internal Revenue Code (IRS). This rate will accrue monthly at 1/12 this annual rate.

Current interest rates

  • Annual rate: 5% (3% IRS rate + 2% IFTA rate)
  • Monthly rate: .00417% (1/12 of 5% annual rate)

If a customer owes $100 of fuel taxes and submits their IFTA tax return 1 month late:

  1. $100 fuel tax owed x .00417% interest for 1 month the return was late = .42 cents interest
  2. $100 fuel tax owed + .42 interest for 1 month = $100.42 total due


For more information about completing your return, see IFTA Tax Return Information and Instructions.

How to request copies of your return

To get copies of IFTA tax returns you’ve submitted:

  1. Complete an Washington State IFTA Information Release Request.
    • Service bureaus: Provide a copy of the Power of Attorney signed by your client along with the completed form.
  2. Send us the completed form and any necessary supporting documents:
  3. We’ll send you the information within 5 business days.

How to get the tax rate schedule

To get a copy of the IFTA tax rate schedule for all states:

Note: Please allow 5 business days for us to process your request.

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