The P11D reports the cash value of benefits in kind you received: company car, private fuel, medical insurance, interest-free loans and more. Employers file it by 6 July after the tax year, and HMRC usually collects the tax by adjusting your tax code the following year.
The form is being retired in stages: from April 2027 company cars, fuel and medical benefits must be taxed through payroll in real time, with most other benefits following in 2028, leaving P11Ds only for loans and accommodation. Read our guide to the 2027 payrolling changes, and generate compliant forms meanwhile with the P11D Generator.
£1,500 of private medical cover reported on your P11D leads HMRC to change your code from 1257L to 1107L (£12,570 minus £1,500, last digit dropped). Across the year that collects £300 of tax at basic rate. When the benefit stops but the code does not, you keep overpaying, so check your code whenever a benefit starts or stops.
