# p11dchanges.co.uk — accounting and invoicing software — 2 of 5

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> Probe-verified (tier 2 of 3). Last checked 2026-09-26. 2 of 5 capability checks passed. 2 unknown.

- host: p11dchanges.co.uk
- url: https://p11dchanges.co.uk/
- category: accounting and invoicing software
- type: business
- country: GB
- language: en-GB

## Probe-verified · tier 2 of 3

Probed live on 2026-09-26 against rubric v1.2. 2 of 5 checks passed. 2 unknown.

- UNKNOWN — Markdown negotiation (`Accept: text/markdown`)
- UNKNOWN — Markdown twin at a predictable URL (`/page.md`)
- PASS — llms.txt (`/llms.txt`)
- PASS — API catalog (`RFC 9727`)
- FAIL — MCP endpoint answers tools/list (`initialize → tools/list, no credentials`)
  - ABSENT — MCP server card (`/.well-known/mcp/server-card.json`): absent; not scored
  - Platform-supplied: not applicable — no MCP endpoint answered; not scored
- FAIL — Other agent files at well-known paths (`agent-skills/index.json · oauth-authorization-server · oauth-protected-resource · http-message-signatures-directory`): none found; not scored

## Summary

Information on the abolition of P11D forms in the UK from April 2027, detailing mandatory payrolling of benefits in kind such as cars, fuel, vans, and medical benefits, with phased implementation through 2028 for employers.

## Context

141 sites in this index share the category "accounting and invoicing software"; 26 are transactional.

## How we grade

- tier 1 — **Declared**: The site says agents are welcome in its robots.txt. A permission, not a capability.
- tier 2 — **Probe-verified** (this site): We fetched the site and tested each signal ourselves. Dated, repeatable, re-checked on a schedule.
- tier 3 — **Behaviourally verified**: An agent completed the action end to end — booked, bought, submitted — and it worked.

## About this record

Known Good probes sites live and publishes what was tested and when.
Method: https://knowngood.sh/about.md · Rubric: https://knowngood.sh/benchmark

How we found this site: probe discovery. This site didn't declare agent access — we found it by checking the open web. Everything above was tested the same way, against the same rubric, on the date shown. [How we choose what to check, and how to opt out](https://knowngood.sh/bot)

## Where this sits

- United Kingdom: https://knowngood.sh/country/GB
- business: https://knowngood.sh/type/business
- accounting and invoicing software: https://knowngood.sh/category/accounting-invoicing-software
- accounting and tax services (also in): https://knowngood.sh/category/accounting-tax-services
- Browse: https://knowngood.sh/browse
- Rubric: https://knowngood.sh/benchmark