The UK is changing how employee benefits in kind are taxed, and while it is being presented as an administrative simplification, it changes what anyone running payroll has to do each month, and it changes what employers and employees should expect from their pay. For decades, benefits like a company car or private medical insurance were reported once a year, after the tax year ended, on a form called the P11D. The reform makes payrolling those benefits mandatory: instead of one report after the fact, the taxable value of the benefit is taxed inside the regular payroll run, in real time. Let me set out what changes, what to watch for, and what it means for both sides of the payslip.
What happens today, and what changes
Under the current system, most benefits are taxed retrospectively. The employer provides the benefit during the year; after the year ends it files a P11D showing the value of each employee's benefits and a P11D(b) for the employer National Insurance due on them. HMRC then claws the income tax back gradually by adjusting the employee's tax code over the following year. The defining feature is that it is annual and backward-looking: the benefit calculation never touches the employee's monthly pay during the year.
Payrolling itself is not new: employers have been able to payroll most benefits voluntarily since April 2016. What the reform (confirmed at the 2024 Autumn Budget) changes is that it makes payrolling mandatory and phases the P11D out for payrolled benefits. Once it applies, the value of a benefit is added to the employee's taxable pay each pay period and the tax on it is collected in real time through the regular payroll submission to HMRC. On timing: mandatory payrolling was originally planned for April 2026, then postponed by HMRC (announced 28 April 2025) to 6 April 2027. HMRC has since confirmed a phased rollout: from 6 April 2027 for company cars, car fuel, vans, van fuel, and employer-provided medical benefits, extending to most other benefits from 6 April 2028. Employment-related loans and living accommodation are excluded from mandatory payrolling and stay on voluntary payrolling or the P11D. The direction is settled: the reform moves benefits out of an annual form and into the monthly pay run.
What people running payroll need to watch for
The practical shift is that a benefit calculation that used to be an annual task becomes a monthly one, and the things that were forgiving about the old system stop being forgiving.
The first thing to watch is that benefits now have to be valued and taxed every pay period, not reconciled once at year-end. That puts a premium on having accurate, up-to-date benefit information flowing into payroll throughout the year, because whatever value is used each month is what the employee is taxed on that month.
The second is mid-year change. Benefits move around constantly: a company car is swapped, medical cover starts partway through the year, a benefit ends when someone leaves. Under the old system those changes were all netted out on one form after year-end. Now each change has to be reflected in payroll promptly, because the tax is being collected as you go rather than trued up later.
The third is that a benefit is taxable but is not cash. The value of the benefit increases the amount of pay the employee is taxed on, but it does not increase the money they actually receive. There is also a long-standing protection that the income tax taken in any period cannot exceed half of the employee's cash pay, so for someone with a large benefit and modest salary the tax can spill into later periods rather than all landing at once. That is a normal outcome to expect, not an error.
The fourth is that employer National Insurance on benefits is a separate charge (Class 1A) and does not simply move in step with the income tax. Payrolling the tax does not turn a benefit into ordinary salary for National Insurance purposes, so the two have to be kept distinct.
And the fifth, which ties the rest together, is that mistakes are no longer quiet. Under the P11D, a wrong value was corrected once, in arrears, on a single form. When benefits are payrolled, an incorrect value flows straight into the employee's tax and take-home pay that month and keeps doing so until it is corrected. The cost of a wrong figure moves from a tidy year-end adjustment to a visible, recurring effect on someone's pay.
What it means for employers
For employers, the main change is one of discipline rather than a new liability. The benefits you provide have not changed and, in most cases, neither has the total tax due; what changes is that the information has to be right monthly rather than assembled once a year. Employers will need to register to payroll benefits before the start of the tax year, keep benefit data current as circumstances change, and retire the P11D for benefits that are payrolled, while still accounting for the employer Class 1A National Insurance. The upside is real: no year-end scramble to compile P11Ds, and fewer surprise tax-code adjustments landing on employees months after the fact. The cost is that benefit data becomes part of the monthly payroll cycle and has to be treated with the same care as pay.
What it means for employees
For employees, the change makes the tax on benefits more predictable. Under the current system, the tax on a benefit is usually collected after the fact: HMRC adjusts the person's PAYE tax code (the figure that tells the employer how much of their pay is tax-free) to recover the tax over a later period, which is why people receive unexpected tax-code notices and see their take-home move for reasons they cannot easily place. This is a PAYE mechanism, not a change in the tax rules. Under payrolling, the tax on the benefit is simply deducted each payday, in the month the benefit applies, so there is no later code adjustment needed to collect it. The one thing worth explaining to employees is that a benefit will appear as extra taxable pay that does not increase the amount transferred to their bank, because they are being taxed on something they receive in kind rather than in cash.
The bottom line
The reform is not, at its core, about a form disappearing. It moves benefits in kind from an annual, after-the-fact calculation into the monthly payroll run, which means each benefit value has to be right the first time, every period, for every affected employee. That is a higher standard than the P11D ever demanded, and it means benefit information has to be kept accurate and up to date throughout the year rather than assembled once at year-end. Flux values and taxes each benefit correctly every period, keeps the employer National Insurance on the right footing, and reports it in real time, so the move to monthly reporting produces correct, steady pay for employees instead of recurring monthly errors.
Mehmood Deshmukh
CTO & Co-Founder