Company cars can be a tax-efficient perk — or an expensive mistake — depending on how they’re structured and used. We see this go wrong a lot, especially with directors of owner-managed companies.
This guide breaks down what company car expenses are allowed, what counts as a taxable benefit, and what HMRC won’t allow, so you can stay compliant and avoid nasty surprises.
A company car is a vehicle:
• Owned or leased by a limited company
• Made available to an employee or director
• Used privately, even occasionally
If there’s any private use (including commuting), HMRC treats it as a Benefit in Kind (BIK). That benefit is taxable on the individual and usually triggers Class 1A National Insurance for the company.
Company car tax is based on:
1. The list price of the car (not what you paid)
2. The CO₂ emissions
3. The fuel type
4. The BIK percentage set by HMRC
Lower emissions = lower tax. Electric cars currently attract the lowest BIK rates.
These costs are allowable business expenses for the company:
Purchase or Lease Costs
• Capital allowances (for qualifying cars)
• Lease payments (subject to CO₂ restrictions)
Running Costs
• Insurance
• Vehicle Excise Duty (road tax)
• Servicing & repairs
• MOTs
• Breakdown cover
• Tyres
• Cleaning & valeting (reasonable)
Business Fuel
• Fuel used exclusively for business journeys
• Mileage logs should be kept (this matters)
This is where people trip up:
Private Fuel (Without Reimbursement)
If the company pays for private fuel and you don’t reimburse it:
• A fuel benefit charge applies
• This is often more expensive than paying privately
Personal Fines & Penalties
• Parking tickets
• Speeding fines
• Congestion charge penalties
HMRC treats these as personal costs, not business expenses.
Personal Use Disguised as Business
Claiming:
• School runs
• Shopping trips
• Holidays
as “business mileage” is a red flag.
If challenged, HMRC can:
• Disallow expenses
• Raise backdated tax
• Apply penalties and interest
Important one: Home → office = private travel
Even if:
• You’re a director
• You work long hours
• You “need the car”
Commuting is not business mileage in HMRC’s eyes.
Electric vehicles (EVs) are currently the most tax-efficient company cars in the UK.
Benefits:
• Very low BIK rates
• No fuel benefit issue (electric ≠ fuel)
• Lower running costs
• Corporation tax relief still available
This is why many directors are switching to EVs through their companies.
For many small business owners, owning the car personally and claiming mileage can be simpler.
Mileage Rates (HMRC Approved):
• 45p per mile (first 10,000 miles)
• 25p per mile thereafter
No BIK. No fuel benefit. Less admin.
A company car only really shines when:
• It’s electric or very low emission
• The business genuinely needs it
• The numbers stack up long-term
Common Company Car Mistakes We See
• Not reporting the car on a P11D
• Paying for private fuel accidentally
• No mileage records
• Assuming “director = exempt” (not true)
• Choosing the wrong vehicle purely on price
Company cars are not automatically tax-efficient — but structured correctly, they can work very well.
Before buying or leasing:
• Run the BIK numbers
• Compare against mileage claims
• Consider EV options
• Get advice before signing the agreement
Fixing it later is usually more expensive.
At Xenith, we help directors and business owners:
• Choose the most tax-efficient option
• Stay fully HMRC-compliant
• Avoid overpaying tax on benefits
If you’re thinking about a company car — or already have one and aren’t sure it’s set up correctly — it’s worth a quick review. Contact us for advice and assistance!
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2026 Xenith Wealth. All rights reserved