P11D Calculator (UK)
Employer-provided benefits like a company car, private medical insurance or a low-interest loan are reported on form P11D and taxed at your marginal rate. See your total benefit value and the annual tax cost.
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Each benefit's cash equivalent value goes onto your P11D and is added to your taxable income — usually collected by adjusting your tax code. A £35,000 company car at 30% BIK rate adds £10,500 to your income; for a 40% taxpayer that's £4,200/year in tax (£350/month).
Your employer also pays Class 1A National Insurance at 15% on the total benefit value — for 2026/27 a £10,500 car BIK costs them an extra £1,575 in NI. That's why salary sacrifice for ultra-low-emission EVs and pensions remains so popular.
Your benefits-in-kind
Only loans averaging over £10,000 trigger a BIK. HMRC's official rate of interest is 3.75% (since 6 April 2025).
What this means for your take-home pay
P11D tax is normally collected by reducing your tax-code allowance — so a £10,500 benefit cuts your tax-code allowance from 1257L to roughly 207L. Result: more income tax taken at source each month, with the same net effect as paying the BIK tax separately.
If you're considering switching a benefit (typically a company car), an EV is almost always the most tax-efficient option — 4% BIK in 2026/27 vs 26–37% on a typical petrol or diesel car. Salary-sacrifice EV schemes can save a higher-rate payer over £3,000/year versus an equivalent petrol car.
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