P11D(b): reporting and paying Class 1A National Insurance

Who needs it

• Every employer that owes Class 1A National Insurance on expenses or benefits provided in the tax year.
• Employers who payroll benefits: payrolling covers the tax, but the Class 1A still goes on a P11D(b).
• Employers filing P11Ds: the P11D(b) goes in with them as the summary of Class 1A owed.

What you need before you start

• The value of every taxable expense and benefit you provided in the tax year, payrolled or not.
• Your total Class 1A National Insurance figure.
• Your PAYE Online login (fewer than 500 employees) or payroll software (500 or more).

How to file P11D(b)

1. 1Total the taxable expenses and benefits for all employees, including any you payrolled.
2. 2Work out the Class 1A National Insurance due on them.
3. 3File the P11D(b) online by 6 July after the end of the tax year, with any P11Ds.
4. 4Pay the Class 1A so it reaches HMRC by 22 July, or by 19 July if you pay by cheque.
5. 5If you find an error later, file a P11D(b) correction online showing the corrected total, not the difference.

What the P11D(b) does

The P11D(b) reports the total Class 1A National Insurance you owe on all the expenses and benefits you provided in the tax year. If you also file P11Ds, it goes in with them by the same deadline.

HMRC's payrolling guidance is explicit that Class 1A applies whether you payroll benefits or report them on a P11D, and that you still need to file a P11D(b). That doesn't change when payrolling becomes mandatory from 6 April 2027.

Deadlines and penalties

The P11D(b) is due by 6 July after the end of the tax year. Class 1A must be paid by 22 July, or 19 July if you pay by cheque. If you have a PAYE Settlement Agreement, the tax and Class 1B on it are due by 22 October (19 October by cheque).

HMRC charges a penalty for each 50 employees, for each month or part month the P11D(b) is late. Paying late brings separate penalties and interest.

Filing and corrections

File online through PAYE Online if you have fewer than 500 employees, or through payroll software if you have 500 or more. Paper is accepted only if you've stopped trading; a paper P11D(b) lists all employees who need a P11D and a summary of Class 1A, and goes to P11D and P11D(b), HM Revenue and Customs, BX9 1WE.

To correct an earlier P11D(b), use the P11D(b) correction form online and show the total Class 1A you owe, not the change.

Common mistakes

• Skipping the P11D(b) because every benefit was payrolled. Class 1A is still due and still reported on it.
• Showing only the difference on a correction. HMRC asks for the total Class 1A you owe.
• Filing on time but paying late. Late payment brings its own penalties and interest.