What is a benefit in kind (BIK)?

How BIK tax actually works

The basic mechanic: HMRC calculates a "cash equivalent" for each benefit, adds it to your taxable income, and adjusts your tax code to collect the tax monthly. Your salary on the payslip stays the same, but more tax comes off.

• The cash equivalent is the BIK value: HMRC's calculated cost of the perk to you, not always its market price.
• Income tax is charged at your marginal rate (20%, 40% or 45%) on the cash equivalent.
• Class 1A NI is paid by the employer at 15% (2026/27) on the cash equivalent. You don't pay employee NI on BIKs unless they're cash vouchers.
• Reporting goes via the P11D form each July, or "payrolled" each pay period if your employer has opted in.

So a £1,000 BIK costs you £200/£400/£450 in income tax (basic/higher/additional). Your employer pays £150 of NI on top. Total cost of the benefit to your household: 20-45% of its cash-equivalent value.

Common BIKs and how they're valued

Some perks look like BIKs but are explicitly exempt — bicycles under Cycle to Work, workplace nurseries, employer pension contributions, and one mobile phone per employee.

Worked example: BIK on a Tesla Model 3

Tesla Model 3 list price £42,000. Pure electric, so the BIK rate is 4% in 2026/27.

• BIK cash equivalent = £42,000 × 4% = £1,680 a year
• Income tax (40% bracket) = £672
• Employer Class 1A NI = £252 (paid by employer, not you)
• Net cost to you of running a £42,000 car: £672 a year of tax

That's why electric company cars are extraordinarily tax-efficient — the BIK rate is artificially low to incentivise EV uptake. By contrast, the same list-price petrol car with high CO₂ might attract a 30% BIK rate, costing the same person £5,040 a year of tax.

Common BIK mistakes

Sources and methodology

BIK rates and rules from gov.uk/expenses-and-benefits-a-to-z and HMRC's Employment Income Manual. Company car CO₂ tables from gov.uk/government/publications/rates-and-allowances-tax-and-tax-credits. Class 1A employer NI rate from gov.uk/national-insurance-rates-letters.

UK Tax Drag is not authorised by the Financial Conduct Authority and does not provide regulated financial advice — see the content disclaimer for the full position. The methodology page documents how every calculator is built and reviewed.

Related

• Company car BIK calculator — precise tax on company car for petrol, diesel, hybrid or electric
• How company car tax rates work — the 3% to 37% scale, fuel benefit, and tax-year changes
• P60 vs P45 vs P11D — where BIK appears on your payroll paperwork
• What is a UK tax code? — how BIK shifts your tax code
• Full UK money glossary
• FAQ library

P11D, payrolling and the employer's Class 1A NI

There are two routes by which the tax on a benefit reaches HMRC, and which one your employer uses determines when you actually pay.

• P11D route: after the tax year ends, your employer files a P11D for each employee by 6 July, listing the cash equivalent of every benefit. HMRC then changes your tax code for the following year to claw back the tax in twelve monthly instalments. This means there is always a lag — a benefit you received last year is taxed through this year's code.
• Payrolling route: the employer registers to payroll benefits before the tax year starts, then adds the cash equivalent to your taxable pay each period. PAYE collects the tax in real time, and no P11D is needed for those benefits. From April 2026 the government is moving towards making payrolling of most benefits mandatory, so this route is becoming the norm.

Either way, the employer separately pays Class 1A National Insurance at 15% (2026/27) on the total cash equivalent of reportable benefits, due by 22 July after the tax year. Class 1A is an employer-only charge — you never pay employee National Insurance on a standard benefit in kind, which is one reason a perk can be slightly more tax-efficient than the equivalent gross salary, even before any pension wrapper.

Trivial benefits — the £50 exemption

Not every perk is taxable. The trivial benefits exemption lets an employer give a benefit completely free of tax and National Insurance provided all four conditions are met:

• the cost is £50 or less per benefit (including VAT);
• it is not cash or a cash voucher (store gift cards are fine);
• it is not a reward for work or performance; and
• it is not part of the employee's contract.

Typical examples are a birthday gift, a turkey at Christmas, or flowers for a life event. There is no annual cap for ordinary employees, but directors of close companies are capped at £300 of trivial benefits per tax year. Crucially the £50 is a cliff edge, not an allowance: a single gift costing £51 is taxable in full, not just the £1 over the limit.

Worked example: how a BIK reduces take-home pay

Suppose you earn £48,000 and your employer adds private medical insurance worth £1,200 a year. Your salary on the payslip does not change, but the £1,200 cash equivalent is stacked on top of your pay for tax purposes.

• Part of your income now sits above the £50,270 higher-rate threshold. The £1,200 benefit straddles the basic and higher-rate bands, but assume for simplicity it is taxed at your marginal 20% here: tax = £240 a year (£20 a month off your take-home through your tax code).
• If instead you were already a 40% taxpayer, the same £1,200 benefit would cost £480 a year.
• Your employer separately pays Class 1A NI of £1,200 × 15% = £180.

The key point for budgeting: a benefit never reduces the gross salary figure, so it is easy to miss. It quietly lowers your monthly take-home via a reduced tax-code allowance. Always reconcile a new perk against the next payslip so an incorrect cash-equivalent does not go unnoticed.

Salary-sacrifice benefits and the OpRA rules

Many benefits are offered through salary sacrifice, where you give up part of your gross pay in exchange for the perk. Since the 2017 Optional Remuneration Arrangement (OpRA) rules, the tax advantage of most sacrifice schemes was removed: you are now taxed on the higher of the cash equivalent of the benefit or the salary you gave up. In practice that means swapping salary for, say, a gym membership no longer saves income tax.

However, OpRA deliberately carved out several benefits that retain their full tax and National Insurance advantage even through salary sacrifice:

• employer pension contributions;
• the Cycle to Work scheme;
• employer-provided childcare and workplace nurseries; and
• ultra-low-emission and electric company cars (emissions of 75g/km or below).

This is why an electric car via salary sacrifice remains one of the most effective remaining perks: you sacrifice gross salary, escape both income tax and employee National Insurance on the sacrificed amount, and are taxed only on the very low EV cash equivalent shown in the table above. For everything outside the carve-outs, treat a salary-sacrifice perk as broadly tax-neutral and judge it on convenience rather than tax saving.