P11D Benefits Tax Calculator UK 2025

Calculate the tax on your benefits in kind including company car, private medical, gym, loans, and more. See employee tax and employer Class 1A NI for each benefit.

Benefits in kind are taxable perks provided by your employer on top of salary, and they must be reported on form P11D. HMRC data shows that company cars, private medical insurance, and beneficial loans are the three most commonly reported benefits, affecting over 4 million UK employees each year.

The tax you pay depends on the cash equivalent value of the benefit and your income tax rate. Employers also pay Class 1A National Insurance at 13.8% on the value of benefits. Understanding the tax cost helps you decide whether a benefit is worth accepting or whether you would be better off with a higher salary instead.

Enter each benefit you receive and its value. The calculator shows the tax payable by you as the employee and the Class 1A NI cost to your employer for every benefit, so both sides understand the true cost.

How it works

  1. Select your income tax rate (20%, 40%, or 45%).
  2. Add each benefit in kind with its cash equivalent value.
  3. View the employee tax, employer NI, and total tax cost for each benefit and overall.

Written by the CalcStack team · Last updated April 2026

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Frequently asked questions

What is a P11D?▾
A P11D is a form that employers use to report benefits in kind (BIK) and expenses provided to employees. Common benefits include company cars, private medical insurance, gym memberships, and interest-free loans. The P11D must be submitted to HMRC by 6 July following the end of the tax year.
How is benefit in kind (BIK) tax calculated?▾
BIK tax is calculated by determining the cash equivalent value of the benefit, then taxing it at the employee's marginal income tax rate. For example, if private medical insurance costs £1,200/year and you are a 40% taxpayer, the tax is £480. The employer also pays Class 1A NI at 13.8% on the BIK value.
How does company car BIK work?▾
Company car BIK is based on the car's list price multiplied by a percentage determined by the CO2 emissions. Electric cars have a 2% BIK rate, while petrol/diesel cars range from 8% to 37%. For example, a car with a £35,000 list price and 20% BIK rate creates a £7,000 annual BIK value.
What is the fuel benefit charge?▾
If your employer pays for private fuel in a company car, an additional fuel benefit charge applies. It is calculated by multiplying a fixed amount (£27,800 for 2025/26) by the same BIK percentage as the car. For a 20% BIK car, the fuel benefit is £5,560. It often makes more sense to pay for private fuel yourself.
What is Class 1A National Insurance?▾
Class 1A NI is paid by the employer at 13.8% on the total value of all benefits in kind. This is in addition to the regular employer NI paid on salary. For £10,000 in total BIK, the employer pays £1,380 in Class 1A NI. It is due by 22 July (19 July if paying by post).
Is private medical insurance a taxable benefit?▾
Yes. The full cost of private medical insurance paid by your employer is a taxable benefit in kind. The BIK value is the premium paid. If your employer pays £1,500/year for your policy and you are a 40% taxpayer, you pay £600 in tax. Family cover has a higher BIK value than individual cover.
Are interest-free loans a taxable benefit?▾
Interest-free or low-interest loans from your employer are a taxable benefit if the total outstanding balance exceeds £10,000 at any point in the tax year. The BIK value is the difference between interest at HMRC's official rate (currently 2.25%) and any interest you actually pay.
What is the excess mileage benefit?▾
If your employer reimburses you for business mileage above the HMRC approved rates (45p for the first 10,000 miles, then 25p per mile), the excess is a taxable benefit. If your employer pays 50p per mile and you drive 15,000 business miles, the excess on the first 10,000 is 5p x 10,000 = £500, plus 25p x 5,000 = £1,250.
Can I salary sacrifice to reduce BIK?▾
Yes. Salary sacrifice arrangements for certain benefits (pension, childcare, cycle-to-work, ultra-low emission cars) can reduce your taxable income and BIK. However, since April 2017, most other salary sacrifice arrangements offer no tax advantage as the BIK is charged at the higher of the salary given up or the benefit value.
When do I need to submit a P11D?▾
Employers must submit P11D forms to HMRC by 6 July following the end of the tax year. P11D(b) forms (summarising Class 1A NI due) have the same deadline. Employees must receive a copy of their P11D by the same date. Late submissions attract penalties of £300 per form.

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© 2026 CalcStack — a Flavoureak UK Ltd product. BIK rates and thresholds based on 2025/26 published rates. This calculator provides estimates only and is not financial or legal advice.