Company Car Tax Calculator
Calculate your benefit in kind tax for the 2025/26 tax year and beyond. Enter your vehicle details below to see how much tax you’ll pay.
Calculation Breakdown
How Does Company Car Tax Work?
When your employer provides you with a company car for private use, HMRC considers this a benefit in kind. You pay income tax on this benefit, and the amount depends on several factors working together to determine your final liability.
The Calculation Formula
Your company car tax follows this straightforward formula:
Annual Tax = Taxable Benefit × Your Income Tax Rate
The P11D value represents the car’s list price when new, including VAT, delivery charges, and any factory-fitted accessories. The BIK percentage depends primarily on the vehicle’s CO₂ emissions and fuel type.
What Affects Your Tax Rate?
Several elements influence how much you’ll pay:
CO₂ Emissions: Lower emissions mean lower tax. Electric vehicles sit at just 2% for 2025/26, whilst high-emission petrol and diesel cars can reach 37%. The government uses this system to encourage environmentally friendly choices.
Fuel Type Matters: Diesel vehicles that don’t meet the RDE2 standard face an additional 4% supplement, making them more expensive to tax. Petrol and RDE2-compliant diesel cars use the standard rates based solely on emissions.
Electric Range for Hybrids: Plug-in hybrid vehicles benefit from lower rates if they can travel further on electric power alone. A hybrid with 130 miles of electric range pays less tax than one managing only 20 miles.
Your Personal Tax Band: Higher earners pay more. Someone in the 45% tax bracket pays more than double what a basic-rate taxpayer pays on the same car.
BIK Rates Explained
Benefit in kind rates change annually and vary significantly based on emissions. Here’s what you can expect for different vehicle types in 2025/26:
| Vehicle Type | CO₂ Range (g/km) | BIK Rate 2025/26 | Example Annual Tax* |
|---|---|---|---|
| Pure Electric | 0 | 2% | £160 |
| Hybrid (130+ miles) | 1-50 | 5% | £400 |
| Hybrid (70-129 miles) | 1-50 | 8% | £640 |
| Hybrid (40-69 miles) | 1-50 | 12% | £960 |
| Hybrid (30-39 miles) | 1-50 | 14% | £1,120 |
| Low Emission Petrol | 51-75 | 16-19% | £1,280-£1,520 |
| Average Petrol/Diesel | 100-150 | 25-32% | £2,000-£2,560 |
| High Emission | 150+ | 33-37% | £2,640-£2,960 |
*Based on £40,000 P11D value and 20% tax rate
Future Year Rates
The government has confirmed BIK rates through 2027/28. Electric vehicles will see gradual increases:
- 2025/26: 2%
- 2026/27: 3%
- 2027/28: 4%
For conventional vehicles, rates typically remain stable or increase slightly year-on-year, though the government may adjust these to meet environmental targets.
Real-World Examples
Example 1: Electric Vehicle
Vehicle: Tesla Model 3
P11D Value: £42,000
Emissions: 0 g/km
Your Salary: £45,000 (40% taxpayer)
Calculation:
Taxable Benefit = £42,000 × 2% = £840
Annual Tax = £840 × 40% = £336
Monthly Cost = £28
Example 2: Hybrid Vehicle
Vehicle: BMW 330e (50-mile electric range)
P11D Value: £38,000
Emissions: 35 g/km
Your Salary: £30,000 (20% taxpayer)
Calculation:
Taxable Benefit = £38,000 × 12% = £4,560
Annual Tax = £4,560 × 20% = £912
Monthly Cost = £76
Example 3: Conventional Diesel
Vehicle: Audi A4 Diesel (Non-RDE2)
P11D Value: £35,000
Emissions: 125 g/km
Your Salary: £55,000 (40% taxpayer)
Calculation:
Base BIK = 30%, Diesel Supplement = +4% = 34%
Taxable Benefit = £35,000 × 34% = £11,900
Annual Tax = £11,900 × 40% = £4,760
Monthly Cost = £397
These examples demonstrate the substantial tax savings available with low-emission vehicles. The electric vehicle saves over £4,400 annually compared to the diesel, despite having a higher list price.
Fuel Benefit Charges
If your employer pays for fuel you use for private journeys, you face an additional fuel benefit charge. This uses the same BIK percentage as your car tax but applies it to a fixed multiplier set by HMRC.
For 2025/26, the fuel benefit multiplier is £27,800. Here’s how it works:
Fuel Benefit Tax = £27,800 × BIK % × Your Tax Rate
For a car with 25% BIK and 40% tax rate:
£27,800 × 25% × 40% = £2,780 annual tax
Many employees find that paying for their own private fuel costs less than this tax charge, particularly if they don’t drive many private miles. Consider carefully whether accepting free fuel actually saves you money.
Frequently Asked Questions
Common Mistakes to Avoid
Using the Wrong P11D Value
Many people confuse the purchase price they negotiated with the official P11D value. The P11D value is always the manufacturer’s list price when new, regardless of any discounts your employer received. Adding expensive options increases this figure, raising your tax liability.
Forgetting the Diesel Supplement
Non-RDE2 diesel vehicles face a 4% supplement, capped at the maximum 37% rate. This catches out many diesel car drivers who calculate using standard petrol rates. Always check whether your diesel meets RDE2 standards.
Ignoring Partial Year Adjustments
Starting or ending a company car mid-year requires prorating. Some people calculate a full year’s tax even when they’ve only had the car for six months. Only complete months count, which can significantly reduce your liability.
Accepting Free Fuel Without Calculating the Cost
The fuel benefit charge often exceeds the value of free fuel, especially for low-mileage drivers. Calculate the tax cost against your expected private fuel spend before accepting this benefit.
Electric vs Petrol vs Diesel: Tax Comparison
Choosing between fuel types dramatically affects your tax bill. Here’s a direct comparison using a £40,000 car for different taxpayers:
| Fuel Type | Typical CO₂ | BIK Rate | 20% Taxpayer | 40% Taxpayer |
|---|---|---|---|---|
| Electric | 0 g/km | 2% | £160/year | £320/year |
| Plug-in Hybrid (60 miles) | 30 g/km | 12% | £960/year | £1,920/year |
| Petrol (Efficient) | 120 g/km | 28% | £2,240/year | £4,480/year |
| Diesel RDE2 | 115 g/km | 28% | £2,240/year | £4,480/year |
| Diesel Non-RDE2 | 115 g/km | 32% | £2,560/year | £5,120/year |
| Performance Petrol | 200 g/km | 37% | £2,960/year | £5,920/year |
The savings with electric vehicles become even more pronounced over multiple years. A higher-rate taxpayer choosing electric over a conventional petrol car saves over £4,000 annually, or £16,000+ across a typical four-year lease.
What Employers Need to Know
Employers face their own obligations when providing company cars. You must report the benefit to HMRC and pay Class 1A National Insurance contributions at 13.8% on the taxable benefit value.
Reporting Requirements
You can report company car benefits either through payroll in real-time or via P11D forms by 6th July following the tax year end. Payrolling benefits often proves simpler administratively and helps employees see the impact on their tax position immediately.
Class 1A NIC Payment
Class 1A National Insurance on benefits must be calculated, reported on form P11D(b), and paid by 22nd July (19th July for cheque payments). This represents a significant cost that employers should factor into their total fleet expenses.
For an employee with a £40,000 car at 25% BIK:
Taxable Benefit = £10,000
Employer’s Class 1A NIC = £10,000 × 13.8% = £1,380 annually
The shift towards electric vehicles benefits employers too. Lower BIK rates mean reduced Class 1A NIC payments, creating cost savings alongside environmental benefits.