Company Car BIK & Class 1A 2026-27 (UK) by ReadyStack

Type the P11D price, CO₂ and electric range. Get the 2026-27 appropriate percentage, the driver's income tax and the employer's Class 1A at 15% — before the P11D(b) goes in.

1. Unzip this folder somewhere permanent.
2. Open chrome://extensions and turn on Developer mode (top right).
3. Click Load unpacked and pick the unzipped folder.
4. Pin the icon and click it.

Works in Chrome, Edge, Brave and any Chromium browser (Manifest V3).

• The 2026-27 appropriate percentage table — Reads HMRC 480 Appendix 2 for 2026-27: 4% at 0 g/km, five electric-range bands for 1-50 g/km, 17% at 51-54 g/km rising 1% per 5 g/km, capped at 37%.
• Employer Class 1A at 15% — Applies the 15% Class 1A rate that replaced 13.8% on 6 April 2025, and shows what the same car would have cost an employer under 2024-25 rates.
• Capital contribution and days unavailable — Caps the employee capital contribution at £5,000, pro-rates the benefit for days the car was unavailable, then deducts any payment made for private use.
• Diesel supplement, only where it is due — Adds the 4% supplement for a car propelled solely by diesel that does not meet RDE2, exempts RDE2 cars, and never lets the total pass the 37% cap.
• P11D(b) late-filing exposure — Shows the £100 per 50 employees (or part of 50) per month that starts running when a P11D(b) is filed after 6 July.
• Working paper and deadline reminders — Full version saves each car as a .csv working paper you keep, and sets 30-day, 14-day and next-day reminders for the P11D(b) date you enter.

| You type | |
|---|---|
| Car P11D list price (incl. delivery and options) | default 42000 |
| CO₂ emissions (0 for a pure EV) | default 0 |
| Electric-only range (1-50 g/km hybrids only) | default 0 |
| Fuel | default Petrol, hybrid or electric |
| Employee capital contribution (capped at £5,000) | default 0 |
| Payment made by employee for private use | default 0 |
| Days the car was unavailable in the tax year | default 0 |
| Driver's income tax rate | default 40 |
| Employees covered by this P11D(b) | default 12 |
| P11D(b) filing deadline (sets your reminders) | default 2027-07-06 |

| It answers | |
|---|---|
| Appropriate percentage, 2026-27 | % |
| Car benefit (cash equivalent) | £/yr |
| Driver's income tax on the car | £/yr |
| Employer Class 1A NIC at 15% | £/yr |
| Same car under 2024-25 rates (2% / 13.8%) | £/yr |
| Extra employer cost vs 2024-25 | £/yr |
| Employer Class 1A over a 3-year lease | £ |
| Late P11D(b) penalty, per month | £/month |

Permissions requested: storage, downloads, alarms, notifications


Free: the calculation in the popup, no key, no limit. Full version ($60): download the result as .csv and deadline reminders - one licence key per person or team seat. Get it: https://buy.polar.sh/polar_cl_MyA9NtPdM7q9pxdv6nV4U0dylRe05HPDCKOFO3y3r66