Follow the steps to fill out the VA DMV RDT 121 online effectively.

1. Use the ‘Get Form’ button to access the VA DMV RDT 121 and open it in your editor of choice.
2. Enter your carrier name and mailing address in the designated fields at the top of the form.
3. Fill in your Virginia Motor Carrier Services (MCS) number and IFTA account number in the appropriate sections.
4. Provide your fleet identifier if applicable.
5. Indicate whether you did not operate tax-qualified motor vehicles this quarter by checking the relevant box if applicable.
6. If you operated in a jurisdiction where a taxable mileage exemption applies, check the appropriate box and enter the jurisdiction and exemption details.
7. Complete the miles per gallon calculation section by entering the fuel type code, total distance traveled, total gallons placed in the vehicles, and calculating the average miles per gallon.
8. Proceed to the fuel tax calculation. Fill in details for each jurisdiction's abbreviation, fuel type code, total distance, taxable distance, taxable gallons, and calculate the net tax due.
9. After entering all necessary information, round totals to the nearest whole gallon and distance. Make sure that the totals match up with your calculations.
10. Finalize the document by reviewing all filled fields for accuracy. Save your changes, then download, print, or share the form as needed.

Complete your VA DMV RDT 121 form online to ensure a smooth submission process.