Trucking: how the math is checked

How the math works

1. Fleet MPG is total miles divided by total gallons bought.
2. Gallons used in a jurisdiction are that jurisdiction's miles divided by fleet MPG.
3. Tax due is gallons used times the rate. Tax paid is gallons bought there times the rate.
4. Net is due minus paid. A negative net is a credit.

Tax rates change, so type in the current rate for each jurisdiction from the official IFTA rate table or your base state's website. This tool does not store any rates and does not check them for you.

Worked example

You drive 1,000 miles in State A and 500 in State B, and you buy 150 gallons in A and 100 in B. Fleet MPG is 1,500 / 250 = 6.0. Say A taxes 0.30 per gallon and B taxes 0.40. In A you used 166.67 gallons, so tax due is 50.00, tax paid is 45.00, and you owe 5.00. In B you used 83.33 gallons, so tax due is 33.33, tax paid is 40.00, and you have a 6.67 credit. The net across both is a 1.67 credit.

How the math works

• Fuel cost per mile is fuel price divided by miles per gallon.
• Variable cost per mile is fuel plus maintenance, tires and anything else you enter per mile.
• Fixed cost per mile is your monthly fixed costs divided by your monthly miles.
• Cost per mile is variable plus fixed. Profit per mile is the rate minus cost per mile.
• Break-even miles are fixed costs divided by the rate minus variable cost per mile.

Run it twice, once with your typical month and once with a slow month, to see how fast a short month eats your profit.

Worked example

Diesel is 4.00 a gallon and the truck gets 6.5 MPG, so fuel is 0.615 per mile. Add 0.15 for maintenance and 0.05 for tires, and variable cost is 0.815 per mile. Fixed costs are 3,000 a month over 10,000 miles, or 0.30 per mile. Your cost per mile is 1.115. At a rate of 2.00 per mile you keep 0.885 per mile, about 8,846 a month. You break even at about 2,532 miles a month.

How the math works

• Effective days are full days plus travel days. If you tick the box, each travel day counts as 0.75.
• Gross allowance is effective days times the daily rate.
• The deduction is the gross allowance times the deductible percentage.

This tool does not know the current rate or your situation. Look up the current daily rate for transportation workers on the IRS website, and ask a tax professional which percentage and day-counting rules apply to you. Keep a log of the nights you were away from your tax home.

Worked example

You were away 198 full days plus 2 travel days. The rate you enter is 60 a day, just as an illustration, and the deductible percentage is 80. With the travel-day box ticked, effective days are 198 + 1.5 = 199.5. The gross allowance is 199.5 x 60 = 11,970, and the estimated deduction is 11,970 x 80% = 9,576.