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How To File Your P11D & P11D(b)

Published 13/06/2025Last updated 17/04/2026

If your company has provided you or your employees with any Benefits in Kind (BIKs), such as a company car, private medical insurance, or interest-free loans, then you'll likely need to file a P11D and a P11D(b) form with HMRC. For more information on what constitutes a Benefit in Kind, see our article here.

For most of our clients, this won't apply but it is still important that you complete the Mighty P11D questionnaire after the tax year ending 5 April passes so we can assess this.

What needs to be filed?

If you've provided benefits, you'll need to file the following:

  • P11D: One per employee or director who received a benefit. This outlines the type and value of the benefit(s).
  • P11D(b): A summary form showing the total Class 1A National Insurance due on all benefits provided by the company.

Deadlines

You must:

  • Submit your P11D declaration to us (you can find this here) by no later than 19 June following the tax year ending 5 April. If you submit the questionnaire after this date Mighty cannot guarantee filing. Please note, even if you don't receive any benefits, we require this declaration to confirm as such. 
  • Submit both forms to HMRC by 6 July following the end of the tax year. For example, if a benefit was received in the tax year ending 5 April, this must be filed by the following 6 July
  • Pay any Class 1A National Insurance by 22 July (or 19 July if paying by post).

How to file your P11D and P11D(b)

We handle the filing process on your behalf but we'll need some information from you first. Here's how it works:

Step 1: Complete the questionnaire in Mighty

To get started, you'll need to fill in the P11D questionnaire directly within Mighty under Taxes (see here). You'll need to provide:

  • The type of benefit provided (e.g. health insurance, company car)
  • The cash equivalent value of each benefit
  • The employee or director details for each person receiving a benefit

If you're unsure how to calculate the value of a benefit, HMRC has calculators and guidance here or just ask us and we'll be happy to help.

Step 2: We review your submission

Once you've submitted the questionnaire, our team will review the information to assess if a P11D is needed and if so, we will begin drafting this for your approval.

Step 3: You approve via email

If you do require a P11D, we'll send you an email for your approval before anything is submitted to HMRC. Simply review and confirm, and we'll take it from there.

If you have any questions, don't hesitate to reach out to your dedicated accountant or support@mightyaccounting.com, we're happy to help.

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