P11D Calculator — Benefit in Kind Tax Calculator | NoMoreJanuary
Free P11D and BIK calculator. Work out the tax on your company car, private medical insurance, or low-interest loan using current HMRC benefit in kind rates.
If your employer provides benefits like a company car,private medical insurance, or a low-interest loan, you owe income tax on the "cash equivalent" of those benefits. The amount depends on the benefit type, your tax bracket, and — for company cars — the vehicle's CO2 emissions and fuel type.
This calculator handles all three benefit types using current HMRC BIK rate tables and official interest rates. Choose a tab, enter your details, and get the annual and monthly tax you'll pay on each benefit.
How this calculator works
- Company car: The cash equivalent is the car's list price (P11D value) multiplied by the BIK percentage rate based on CO2 emissions and fuel type. Your tax is the cash equivalent multiplied by your income tax bracket.
- Private medical: The cash equivalent is simply the annual premium your employer pays. Your tax is that amount multiplied by your tax bracket.
- Low-interest loans: The cash equivalent is the loan balance multiplied by the difference between the HMRC official rate and the rate you actually pay. Loans under £10,000 are exempt.
BIK percentage rates for company cars
The BIK rate for a company car depends on its CO2 emissions (g/km) and fuel type. Lower emissions mean a lower rate — and fully electric cars pay the lowest rate of all. The rates below are for the 2025-26 tax year:
| CO2 emissions (g/km) | Petrol / diesel RDE2 | Diesel non-RDE2 |
|---|---|---|
| 0 (fully electric) | 3% | 3% |
| 1–50 (hybrid, 130+ mile range) | 3% | 7% |
| 1–50 (hybrid, 70–129 mile range) | 6% | 10% |
| 1–50 (hybrid, 40–69 mile range) | 9% | 13% |
| 51–54 | 16% | 20% |
| 55–59 | 17% | 21% |
| 60–64 | 18% | 22% |
| 65–69 | 19% | 23% |
| 70–74 | 20% | 24% |
| 75–79 | 21% | 25% |
| 80–84 | 22% | 26% |
| 85–89 | 23% | 27% |
| 90–94 | 24% | 28% |
| 95–99 | 25% | 29% |
| 100–104 | 26% | 30% |
| 105–109 | 27% | 31% |
| 110–114 | 28% | 32% |
| 115–119 | 29% | 33% |
| 120–124 | 30% | 34% |
| 125–129 | 31% | 35% |
| 130–134 | 32% | 36% |
| 135–139 | 33% | 37% |
| 140–144 | 34% | 37% |
| 145–149 | 35% | 37% |
| 150–154 | 36% | 37% |
| 155+ | 37% | 37% |
Diesel cars that don't meet the RDE2 emissions standard pay a 4% supplement on top of the standard rate, capped at 37%. The 2024-25 rates are 1 percentage point lower across most bands — the calculator applies the correct table automatically based on the tax year you select.
Worked examples
Company car: petrol, £28,000 list price, 110 g/km CO2
In the 2025-26 tax year, a petrol car with 110 g/km CO2 falls in the 28% BIK band. The cash equivalent is £28,000 × 28% = £7,840/year. At the 20% basic rate, you'd pay £1,568/year (£131/month). At the 40% higher rate, you'd pay £3,136/year (£261/month).
Private medical insurance: £1,200 annual premium
The cash equivalent is the full premium your employer pays: £1,200/year. At 20%, you'd pay £240/year (£20/month). At 40%, you'd pay £480/year (£40/month). Unlike company cars, there's no CO2-based rate — the premium is the taxable value.
Low-interest loan: £15,000 at 0% interest
The official rate for 2025-26 is 3.75%. The cash equivalent is £15,000 × 3.75% = £562.50/year (the difference between the official rate and your 0% rate). At 20%, you'd pay £112.50/year (£9.38/month). If the loan balance never exceeded £10,000, it would be exempt entirely.
How the tax is collected
If you file a Self Assessment return, you declare benefits in the "Employment benefits and expenses" section. If you don't file a return, HMRC collects the tax by adjusting your PAYE tax code — reducing your Personal Allowance so the extra tax is spread across the year via your salary. You can't choose which method is used; it depends on whether you're in Self Assessment.
For the full plain-English explanation of how benefits in kind work, how the P11D form reports them, and how to declare them, see our guide tobenefit in kind and P11D forms.
This calculator provides estimates based on HMRC rates. Your actual tax liability may vary depending on your individual circumstances. Always refer to your P11D andHMRC's official guidance.
Frequently Asked Questions
What is a P11D?
A P11D is the form your employer files with HMRC to report the value of benefits they've given you during the tax year — things like a company car, private medical insurance, or a low-interest loan. The "cash equivalent" shown on the P11D is the taxable value of those benefits, and you pay income tax on it at your marginal rate.
How is company car benefit in kind calculated?
The taxable benefit for a company car is based on the car's list price (P11D value) multiplied by a BIK percentage rate. The rate depends on the car's CO2 emissions and fuel type — lower emissions mean a lower rate. Diesel cars that aren't RDE2-compliant get a 4% supplement. Fully electric cars have the lowest rate (2% in 2024-25, 3% in 2025-26).
Do I need to declare benefit in kind on my Self Assessment?
Yes. If you receive benefits in kind from your employer, you need to declare them on your Self Assessment tax return. They go in the "Employment" section under "benefits and expenses." The cash equivalent from your P11D is added to your income and taxed at your marginal rate.
Are loans from my employer always taxable?
No. Loans from your employer with a maximum balance under £10,000 at any point in the tax year are exempt from benefit in kind tax. For loans over £10,000, the taxable benefit is the difference between the official interest rate and the rate you actually pay, applied to the maximum balance.