Reefer fuel log for IFTA and fuel tax
Reefer fuel doesn't move the truck, so it's taxed and reported differently. Keep it apart from the start.
| Date | State | Gallons: truck tank | Gallons: reefer tank | Price ($/gal) |
|---|---|---|---|---|
How to use it
Pick how your reefer gets fuel: from its own tank, filled separately at the pump, or from the truck's tank. Then log each fill: the date, the state and how many gallons went into the truck's tank and the reefer's tank. The rows with numbers are an example; replace them with your receipts.
If your reefer runs off the truck's tank, enter the hour meter readings and your unit's gallons per hour from your own records. The log estimates the reefer's share, which is the kind of reasonable, record-backed estimate the IRS asks for. Print the page each quarter and keep it with your receipts. Nothing you type is saved or sent anywhere.
The credit line is only a number to bring to your tax preparer. It applies to undyed diesel you bought with the federal tax included, and only the person who bought the fuel can claim it. See how to file IFTA and reefer trucking basics.
The rules behind the log
- IFTA counts fuel that propels the truck. The IFTA Articles of Agreement define motor fuels as fuel placed in the supply tank of a qualified motor vehicle (R239), and a licensee reports all fuel placed in the supply tank used to propel it (R820). California's IFTA guide says gallons used in refrigeration units with separate tanks are left out of the IFTA total gallons and MPG.
- Receipts. The IFTA Procedures Manual (P550) says a receipt needs the date, the seller's name and address, the gallons, the fuel type, the price per gallon or total price, the vehicle the fuel went into, and the buyer's name. Mark which tank each fill went into.
- Federal tax. IRS Publication 510 says off-highway business use includes fuel used in a separate motor to run special equipment, such as a refrigeration unit. If the reefer draws from the truck's tank, you must figure how much it used, and a reasonable estimate based on your operating experience and supported by your records is allowed. Form 4136 (2025) line 3 pays $0.243 per gallon for nontaxable use of undyed diesel, and only the ultimate purchaser can claim it.
- Dyed diesel. Pub 510 allows dyed fuel only for nontaxable uses, and the penalty for any other use is the greater of $1,000 or $10 per gallon. Never put it in a tank that feeds the truck's engine.
- State refunds vary. Two examples: California's CDTFA says diesel used to run reefer units is a nontaxable use, refunded on form CDTFA-770-DU within three years of the purchase, with hour meter readings for reefers that share the truck's tank. Missouri's Form 4923 has a line for gallons used in reefer units, due within one year of the purchase or by April 15 of the next year, whichever is later. Check your own state's revenue agency.
- IRS Publication 510, Excise Taxes (Rev. December 2025): off-highway business use, use in separate motor
- IRS Form 4136 (2025), line 3: nontaxable use of undyed diesel fuel
- IRS Instructions for Form 4136 (2025)
- IFTA Articles of Agreement (Jan. 2026): R239 motor fuels, R820 fuel reporting
- IFTA Procedures Manual (Jan. 2026): P550 fuel receipts
- CDTFA Publication 50, California IFTA guide
- CDTFA: diesel fuel refunds for users (reefer units)
- Missouri DOR Form 4923, Non-Highway Use Motor Fuel Refund Claim
This page is general information, not legal or tax advice. Rules change; confirm with FMCSA, the IRS or your state before you file.
Questions carriers ask
Does reefer fuel go on my IFTA return?
IFTA counts fuel placed in the tank that propels the truck. California's IFTA guide says gallons used in reefers with separate tanks are left out. If the reefer shares the truck's tank, all of that fuel goes on the return.
Can I get the fuel tax back on reefer fuel?
The IRS treats fuel used in a separate motor that runs a refrigeration unit as off-highway business use, and Form 4136 has a credit for undyed diesel used that way. Some states also refund their tax, such as California and Missouri. Ask your tax preparer and your state.
Can I use dyed diesel in my reefer?
Dyed diesel is only for nontaxable uses. IRS Publication 510 counts fuel for a separate motor that runs a refrigeration unit as off-highway business use, which is one of them. It must never go in a tank that feeds the truck's engine; the federal penalty is the greater of $1,000 or $10 a gallon.