How to Tell if Someone Is Using Red Diesel?

You can tell someone is using red diesel if you see them filling a road vehicle with visibly red-dyed fuel. It’s illegal for use in most on-road vehicles in the UK since April 2022 and can be reported to HMRC.

What Is Red Diesel?

Red diesel is a dyed version of regular diesel, commonly used in off-road vehicles and machinery such as tractors, generators, and construction equipment. It’s taxed at a lower rate, making it a cost-effective option for non-road use.

Since April 2022, UK regulations have tightened — red diesel is now strictly prohibited in most road vehicles, including personal cars, vans, and lorries.

Is Red Diesel Illegal?

Red diesel isn’t illegal — but using it in road-going vehicles is. It’s intended only for specific applications:

• Agricultural machinery (e.g. tractors)
• Construction equipment
• Heating systems

Using red diesel outside of these permitted purposes is considered fuel tax evasion and is a prosecutable offence under HMRC regulations.

Signs Someone Is Using Red Diesel Illegally

It’s often difficult to tell if someone is misusing red diesel, but there are a few signs:

• You visually spot red-dyed fuel being poured into a road vehicle
• There’s a strong fuel smell in a residential setting
• The vehicle operator boasts about “cheap fuel” in private transport use

What Happens If You’re Caught Using Red Diesel?

When HMRC discovers misuse:

• Vehicle or equipment can be seized
• Illegal fuel is confiscated
• You may have to repay all avoided fuel duty (going back up to 4 years)
• Hefty fines or prison sentences up to 7 years for repeat offenders

HMRC’s Enforcement Actions

HMRC has the authority to:

• Impose civil penalties
• Seize vehicles or equipment
• Deny restoration of seized goods
• Fine businesses for failing to produce fuel records or denying sampling

If you’re caught, you may face all of the above and possibly prosecution for tampering with fuel (e.g. laundering red dye).