It is important to remember that the P46(car) process lets HMRC know about changes to employees’ cars; HMRC use this information to alter their tax code to try and collect the correct tax In-year. However, it is the end of year P11D submission that sends the final financial position, and it is that which HMRC use to finally collect the right amount.

However, it is always good for an employee to be paying as close as possible to the correct tax, so any errors are worth resolving. Before we go too far, there are two basic facts to understand:

  • Just deleting the car from the employee in the P11D Organiser and then running the P46(car) process will NOT solve the issue.
  • If you have already withdrawn or replaced the incorrect car there is nothing you can do in-year to correct it via the P46(car) process – however any corrections will be handled in the P11D at year end.

Once we get past those points, the way to resolve an issue depends on what the error was, as there are several options:

  1. You submitted the correct car with the correct date, but some of the associated details were incorrect (like price, CO2, or fuel type).
  2. You submitted the correct car information, but the date provided was wrong.
  3. You submitted completely the wrong car, but on the right date.
  4. You submitted the wrong car on the wrong date and possibly incorrect information.

1. Right Car, Right Allocation Date, Wrong Information

This is simple to correct, you can go to the employee and edit the car allocation in question - modify the asset and correct the data that was wrong and save the record. The software will pick these changes up and send a P46(car) replacement car (with the same dates), correcting the information.

2. Right Car, Wrong Date

If the correct date a car was provided was earlier than you have sent, you would need to provide the car on the correct date, with an end date the day before the incorrect allocation date (so another allocation).

If the correct date of provision was later, the best you can do within the restrictions of HMRC’s P46(car) process is to withdraw on the same day it was allocated, so minimising the issue for tax coding. To accomplish this, change the allocation and submit a P46(car). Once submitted, you can then provide the car on the right date and submit a P46(car), and then delete the incorrect allocation.

If you have submitted an incorrect withdrawal date, then the action to take would depend on the error:

  1. If you have withdrawn the car too early, you can re-allocate the same car the next day (as long as there is no other car allocated), and then withdraw on the correct day.
  2. If you have withdrawn too late (you want to report an earlier withdrawal datedate), you can't do this with a P46(car), and would need to contact HMRC direct.

3. Wrong Car, Right Date

The P11D Organiser will sort this out quite easily – go to the employee and the car allocation, and simply change the car for the correct one and save, The P11D Organiser will see the change and create a replacement car from the same date, ensuring the employee is only taxed for one car.

4. Wrong Car, Wrong Date, Wrong Information

Sadly, you'll need to contact HMRC direct about issues like this.


The processes above are the best way to handle these situations within the confines of the P46(car) process, however the other option is to call HMRC and let them know about the error and take their guidance.