P11D and Class 1A NIC: the 6 and 22 July Deadlines

P11D, P11D(b) and Class 1A NIC produce more late-filing penalties than any other small-employer obligation. The dates are fixed, the forms are short, and yet every July HMRC adds a fresh batch of £100-per-month charges.

What P11D and P11D(b) actually report

P11D reports taxable benefits in kind for each employee or director. P11D(b) is the employer's declaration and Class 1A NIC return: one per PAYE scheme, regardless of headcount. Both relate to the tax year just ended.

What typically goes on a P11D: company cars and fuel, private medical, interest-free or cheap loans where the balance exceeded £10,000 at any point in the year, gym memberships, non-business travel, assets transferred at undervalue, taxable subscriptions. What doesn't: trivial benefits of £50 or less (non-cash, non-contractual, not linked to performance, capped at £300 per year for close-company directors), and business mileage at HMRC's AMAP rates.

The 6 July filing deadline

For the 2025/26 tax year, P11D and P11D(b) must be filed by 6 July 2026. Online only. HMRC withdrew the paper route in April 2023, and the interactive PDF that used to fill the gap went the same way. Practices still occasionally try to submit on paper and have the filing rejected, which then triggers the same automatic penalty as not filing at all.

19 July vs 22 July: post vs electronic payment

Class 1A NIC for 2025/26 is payable by 22 July 2026 if paying electronically, or 19 July 2026 if paying by post. The rate is 15% for 2025/26, up from 13.8%, with the secondary threshold cut to £5,000 at the same time. Both changes took effect from 6 April 2025.

Calculating Class 1A NIC

Class 1A is 15% of the total cash equivalent of all reportable benefits across the scheme, not per employee. Add the benefit values from every P11D in the scheme, multiply by 0.15, and pay using the Accounts Office reference with the year-suffixed '1A' indicator (the last four characters of the reference become '13' for 2025/26, i.e. ending YY13). Paying to the normal PAYE reference is one of the recurring Class 1A mistakes: HMRC allocates it to the latest open period and chases the Class 1A as unpaid.

Payrolling benefits as an alternative

An employer can payroll benefits by registering with HMRC before 6 April of the relevant tax year. Most BiKs can be payrolled. Employer-provided loans and accommodation were historically excluded, but voluntary payrolling for both opens from 6 April 2026.

Mandatory payrolling for most BiKs was originally scheduled for April 2026. It's been deferred to 6 April 2027. Any client who heard 'it's mandatory next year' back in 2024 and acted on it deserves a quick correction: the rules they planned for don't apply yet.

Even when payrolling, the P11D(b) and Class 1A obligations remain. Class 1A is still 15%, still due 22 July, and the P11D(b) is still notifiable under SI 2001/1004 reg.80. A nil P11D(b) is required if all benefits were payrolled and there's no Class 1A to declare. Silence is not an option.

Penalties and interest for late filing

Late P11D(b): £100 per 50 employees (or part) per month, under FA 2009 Sch.55. A 30-employee scheme that's three months late costs £300. Small, but automatic. Inaccurate P11Ds fall under the FA 2007 Sch.24 tax-geared regime: careless errors attract penalties up to 30% of the potential lost revenue, deliberate concealment up to 100% (200% offshore). Late Class 1A payment carries interest under FA 2009 Sch.53 from 23 July.

Common P11D mistakes to avoid

The recurring errors we see:

• Loan written off in the year but the s175 ITEPA charge not separately reported, and the s188 ITEPA deemed-earnings charge missed entirely, triggering Class 1 NIC the client wasn't expecting.
• Private fuel benefit reported but cash contributions for fuel forgotten on the offset side.
• Payrolling registered after 5 April. The registration only takes effect from the following tax year, so the current year still needs P11Ds.
• Benefits both payrolled and reported on P11D. Pick one, never both.
• Forgetting that EV home charging, where the employer reimburses domestic electricity, is reportable unless it falls within the specific exemption for charging at the workplace.

The pattern across all of these: the deadline isn't the problem. The classification is.