The Form That Catches Employers Out Every July
If you employ staff or run your own limited company, there is a good chance you need to think about P11Ds right now. The form has a quiet deadline of 6 July that sits just after the busier payroll year end, and every summer a fresh wave of employers realise they have missed it. This guide explains what a P11D actually is, what goes on it, when it is due, and the change coming in 2027 that will make the form disappear for most businesses.
We will keep it in plain English. P11Ds are not complicated once you understand the one idea behind them: HMRC wants to tax the value of things you give employees that are not cash wages.
What Is a P11D?
A P11D is a form employers send to HMRC to report benefits in kind, also called expenses and benefits, that they have given to employees or directors during the tax year. A benefit in kind is anything of value an employee receives from their job that is not part of their normal salary and has not already been taxed through payroll. Because it has real value to the employee, HMRC treats it as taxable, even though no extra cash changed hands.
Common examples that go on a P11D include:
- Company cars and the fuel that goes with them
- Private medical and dental insurance
- Interest free or low interest loans to employees above £10,000
- Living accommodation provided by the employer
- Gym memberships and other personal expenses paid by the company
There is one P11D per employee who received reportable benefits. A separate summary form, the P11D(b), reports the total Class 1A National Insurance the employer owes on all those benefits across the whole workforce. Think of the individual P11Ds as the detail and the P11D(b) as the bill.
It helps to be clear about what does not go on a P11D. Salary, bonuses and anything run through your normal payroll are already taxed, so they are excluded. Genuine business expenses that an employee reclaims, such as travel to a client or a hotel for a work trip, are usually exempt and do not need reporting either. The P11D is specifically about the perks that have a personal benefit attached.
Why Benefits in Kind Are Taxed at All
People sometimes feel the P11D is HMRC being awkward, but the logic is fair once you see it. Imagine two employees who both cost their employer £40,000 a year. The first takes the lot as salary and pays income tax and National Insurance on all of it. The second takes £30,000 as salary and £10,000 as a company car, private healthcare and a gym membership. Without a benefit in kind system, the second employee would pay tax on only £30,000 while enjoying the same £40,000 of value. The P11D closes that gap so both are taxed on what they actually receive.
The employee pays income tax on the value of their benefits, usually collected by an adjustment to their tax code so it comes out of future pay. The employer pays Class 1A National Insurance on the same value. For the 2025/26 tax year that Class 1A rate is 15 percent, in line with the rise in employer National Insurance from April 2025, so the cost of running benefits is higher than it was a year ago. That is worth factoring into any decision about offering or withdrawing a perk.
The P11D Deadline for 2025/26
This is the part to write down. For the 2025/26 tax year, which ran to 5 April 2026, the key dates are:
- 6 July 2026: file your P11D and P11D(b) forms with HMRC, and give each employee a copy of their own P11D information.
- 22 July 2026: pay the Class 1A National Insurance shown on your P11D(b) if you pay electronically. If you still pay by post the date is 19 July, but very few employers do now.
P11Ds must be filed online. HMRC closed its paper P11D route a couple of years ago, so you submit either through payroll software or through HMRC's PAYE Online service. If you have no benefits to report but HMRC has issued a P11D(b) notice, you should still tell them there is nothing to declare so the system does not keep expecting a return.
What Happens If You File Late
The penalties are the reason the P11D deserves attention rather than panic. Miss the P11D(b) deadline and HMRC charges £100 for every 50 employees, for each month or part month the return is late. For a small business that is £100 a month, which adds up quickly if a forgotten return sits unfiled over the summer.
There are separate penalties for getting the figures wrong, which can reach up to the full amount of National Insurance underpaid where HMRC decides the error was careless or deliberate. Pay the Class 1A bill late and interest runs on top. None of this is dramatic if you are organised, but it is entirely avoidable money, which is the worst kind to lose.
Company Cars: The Benefit Most People Are Asking About
When employers search for help with P11Ds, the company car is usually behind it, because it is the most common and the most valuable benefit in kind. The taxable value of a company car is not what it cost. It is a percentage of the car's list price, with the percentage set by the vehicle's CO2 emissions. The cleaner the car, the lower the charge.
This is why electric and low emission company cars have been so popular in recent years. Their benefit in kind percentages are far lower than a petrol or diesel equivalent, so both the employee's tax and the employer's Class 1A National Insurance are much smaller. If you are weighing up a company car against a car allowance paid as salary, the benefit in kind rate is the number that decides which is cheaper, and it is a calculation worth doing properly rather than guessing.
For directors of small companies, the company car interacts with how you pay yourself overall. We cover that wider picture in our guide to directors' remuneration, where the salary, dividend and benefits mix all need to be looked at together rather than one at a time.
The Big Change: Payrolling Benefits Becomes Mandatory in 2027
Here is the part that makes 2025/26 different from every year before it. From 6 April 2027, payrolling most benefits in kind becomes compulsory. Instead of reporting benefits once a year on a P11D, employers will run the tax on them through payroll in real time, in the same way salary is taxed every pay period. The Class 1A National Insurance moves into the payroll cycle too.
This was originally planned for April 2026, then deferred by a year to give employers and software providers time to prepare. The practical upshot is that the P11Ds you file by 6 July 2026 are, for most employers, the last full year of the traditional once a year form. After that, the P11D as people know it largely goes away for ordinary benefits.
You do not have to wait. Payrolling benefits is already available voluntarily, and many employers are moving to it now so the 2027 switch is a non event rather than a scramble. It also smooths things out for employees, who see the tax on their benefits spread across the year in small amounts rather than landing as a tax code change later. If you are going to have to do it anyway, doing it early on your own timetable is usually the calmer path. It is worth a conversation with your accountant about whether to register before the start of the next tax year.
Our View
In our experience the P11D causes far more stress than it should, and almost always for the same reason: it is treated as a once a year afterthought rather than something the bookkeeping quietly captures all year round. The businesses that find July painless are the ones whose records already flag a benefit the moment it happens, so the form is a summary of known facts rather than an archaeology project.
Our honest advice is twofold. First, get the 2025/26 return done early and correctly, because the penalties are pure waste. Second, treat the move to mandatory payrolling as a prompt to tidy up how you handle benefits altogether. With Class 1A National Insurance now at 15 percent, some perks cost more than they are worth to the employee, and the run up to 2027 is a sensible moment to review which benefits still earn their place. Good tax planning is not just about filing the form, it is about deciding what should be on it in the first place.
How IAK Can Help
We handle P11Ds for businesses across North London every summer, so the 6 July deadline is routine for us rather than a crisis for you. Our payroll service prepares your P11D and P11D(b), calculates the Class 1A National Insurance, files everything online with HMRC, and gives your employees their copies on time. We also check that benefit in kind tax codes are correct, so your people are not over or under taxed through the year.
Beyond the form, our tax planning and personal tax teams help you decide which benefits are still worth offering at today's rates, and our accounting team can get you set up for payrolling benefits ahead of the 2027 change so the transition is smooth.
If a P11D deadline is looming, or you are not sure whether you even need to file one, contact us for a free consultation and we will tell you exactly where you stand.
Sources
- Expenses and benefits for employers, GOV.UK, on which benefits in kind are reportable and how they are valued.
- PAYE end of year expenses and benefits (P11D), GOV.UK, on filing P11D and P11D(b) forms online.
- Rates and thresholds for employers 2025 to 2026, GOV.UK, on the Class 1A National Insurance rate.
- Payrolling: tax employees' benefits and expenses through your payroll, GOV.UK, on voluntary payrolling and the move to mandatory reporting from April 2027.