Car allowance: how it's taxed, and how to claim mileage on top

A car allowance is a fixed sum your employer pays, usually monthly, because you use your own car for work. In the UK it is taxed like the rest of your pay: it goes through payroll with Income Tax and National Insurance taken off. The part most drivers miss is that HMRC does not treat a flat allowance as a mileage payment. So if your employer pays you less than the approved mileage rate per business mile, which includes paying nothing per mile, you can usually claim tax relief on the difference as well.

Here is how that works, with numbers, and how a car allowance compares with a company car.

Is a car allowance taxable?

Yes. HMRC's manual lists "a fixed amount per month that is not calculated on the basis of business mileage" among the things that are not mileage allowance payments, and says these are normal earnings within PAYE. The same goes for a payment made because you no longer have a company car. Your employer cannot later relabel part of it as expenses either: "the nature of the payment is fixed when it is made."

There is one exception. A lump sum worked out to cover only the business share of the car's standing costs, based on reasonable estimates and reviewed during the year, does count as a mileage allowance payment. HMRC gives the regular-user lump sums paid by many local authority and NHS employers as examples. If your allowance is one of those, it is counted with your per-mile payments in the sums below. Most "£X a month with the job" allowances are not.

Can I claim mileage if I get a car allowance?

Usually, yes. Tax-free mileage works on an approved amount: your business miles for the tax year multiplied by HMRC's rates. If the mileage allowance payments you receive come to less than that, you can claim Mileage Allowance Relief on the gap. A flat car allowance is not a mileage allowance payment, so it does not reduce the gap.

The rate covers all the costs of owning and running the car, so you cannot claim fuel, repairs, insurance or vehicle tax on top. The full background is in our guide to HMRC mileage rates for 2026/27.

A worked example for 2026/27

Priya is a field sales manager. She gets a car allowance of £350 a month and a fuel rate of 12p a mile. This year she drives 9,000 business miles in her own car.

The allowance does not appear in the relief sum at all. It is taxed as pay and that is the end of it. The fuel payments are mileage payments, so they come off the approved amount.

Relief is a deduction, not a cheque for £3,870. At 20% tax, it is worth £774 to Priya; at 40%, £1,548. GOV.UK also notes that the relief cannot be more than the tax you paid that year. If her employer paid nothing per mile, she could claim relief on the whole £4,950.

How to claim it

You can claim for the current tax year and the four before it. Employees can claim online or on a P87 form; if you fill in a Self Assessment return, the claim goes on the return instead.

HMRC wants the evidence first. For mileage that means a copy of your log for each employment, with the reason for every journey and the postcodes where it started and ended. If you have not kept one, start now; our guide to HMRC mileage log requirements shows what a good one looks like.

What about National Insurance?

National Insurance works on a separate scheme, and it is your employer's payroll job rather than something you claim back. Cash paid towards the use of your own car, which GOV.UK calls relevant motoring expenditure, can be National Insurance-free up to a qualifying amount: your business miles in each pay period × 55p, with no drop to 25p after 10,000 miles. Only the excess is added to your pay for Class 1 National Insurance.

Whether a particular car allowance counts is a question of fact. HMRC says a lump sum paid for the use, or potential use, of your own car can be relevant motoring expenditure, but a payment for giving up a company car is not. There is no Mileage Allowance Relief for National Insurance, and an unused qualifying amount cannot be carried into a later pay period. If your employer has never looked at this, their payroll adviser is the one to ask.

Car allowance vs company car

If your employer offers a choice and you take the car instead of the cash, the optional remuneration rules can apply. For a car with CO2 emissions over 75g/km, you are taxed on the higher of the cash allowance you gave up and the car's taxable value. Cars at 75g/km or less are taxed on the normal rules. Which option leaves you better off depends on the car, your miles and your tax rate, so run the numbers both ways before you sign.

For the company car side, including how to avoid the fuel benefit charge, see advisory fuel rates for company cars.

Frequently asked questions

Is car allowance taxable in the UK?

Yes. A flat car allowance is earnings, taxed through PAYE like salary, with National Insurance subject to the qualifying amount rules above.

Does a car allowance count as salary?

For tax, it is treated the same way: it is earnings and goes through payroll. Whether it counts towards your pension, bonus or overtime is down to your contract and the scheme rules, not HMRC.

Does a car allowance cover fuel?

Only if your employer says so. Many pay a separate fuel rate per mile, and that rate counts as a mileage payment. If you get no per-mile payment, the relief is worked out on your full approved amount.

Car allowance vs mileage reimbursement: what's the difference?

Mileage payments up to the approved amount are tax-free and need no reporting. A car allowance is taxed as pay whether you drive 100 miles or 10,000. Many employers pay both, which is why claiming the gap matters.

How much car allowance should I get?

HMRC does not set one; it is whatever your employer offers. When you compare offers, count what the car costs you to run, and the relief you can claim on business miles at 55p.

Where ClaimSnappy fits

ClaimSnappy keeps the mileage side of a car allowance in order. In Settings, set the mileage rate to what your employer pays per mile, or Nothing if the allowance is all you get. Add each trip on the website by typing the start, any stops and the finish, tapping them on the map, or typing the miles. A trip cannot be saved without a reason, and its start and end postcodes are saved with it. Trips are priced at HMRC's rate, 55p then 25p after 10,000 business miles.

When your employer pays less than HMRC's rate, Reports prepares HMRC's own P87, pre-filled and ready to sign, for the difference, with the mileage log behind it and up to five tax years at a time. Lines missing a reason or postcode are flagged first. If your employer also repays costs such as parking, you build that claim and send it yourself, and on a team desk it can go to a manager for approval. Your accountant can see it all in the free accountant portal.

Start with a 30-day trial, no card needed; after that, Solo is £5 a month. See how it works if you claim for yourself or run a team, or compare plans.

ClaimSnappy keeps the records; it does not decide what HMRC will allow. If your allowance is unusual, or you are weighing up a company car, an accountant will earn their fee.