cis-verification

cis-verification is a skill for Claude Code, Codex from Jody09-dotcom/constructionx-skills. It costs 89 tokens per session (1,515 once invoked), scanned A, original, MIT.

A guide for UK contractors using the Construction Industry Scheme, a tax system for payments to construction subcontractors. It covers subcontractor checks and deduction calculations.

In plain words
What is it for?
Use it when onboarding or rechecking a subcontractor, calculating deductions from labour and materials, preparing the monthly CIS300 return, or explaining the scheme.
Why use it?
It helps contractors prepare the information needed for HMRC, the UK tax authority, and work out whether a payment requires a tax deduction.

Skill for Claude CodeCodex

Written for no agent in particular: nothing here depends on one.

Good fit Use it when onboarding or rechecking a subcontractor, calculating deductions from labour and materials, preparing the monthly CIS300 return, or explaining the scheme.

Compare 6 skills from other repositories ↓
Install with agentmods
npx agentmods add skills/jody09-dotcom/constructionx-skills/cis-verification
Install

Getting it into your agent

One page per mod, every tool's command on it. A separate URL per tool would split the same page into five that compete with each other.

Any agent
npx skills add Jody09-dotcom/constructionx-skills --skill cis-verification
Clone the repo
git clone --depth 1 https://github.com/Jody09-dotcom/constructionx-skills

Made for: Claude Code, Codex.

Its marketplace also offers this one on its own, as the plugin cis-verification/plugin install cis-verification after adding the marketplace above.

Wrote this? Show the measurements

A badge with what this costs and how it scanned, read live from this page, so it follows the numbers instead of freezing them. Markdown for a README, HTML for a documentation site or a project page.

agentmods badge for cis-verification

README.md
[![agentmods](https://agentmods.dev/badge/skills/jody09-dotcom/constructionx-skills/cis-verification/github.svg)](https://agentmods.dev/skills/jody09-dotcom/constructionx-skills/cis-verification)
Your own site
<a href="https://agentmods.dev/skills/jody09-dotcom/constructionx-skills/cis-verification"><img src="https://agentmods.dev/badge/skills/jody09-dotcom/constructionx-skills/cis-verification/github.svg" alt="Measured on agentmods" height="20"></a>

Or the 80×15 button, for a site that already has a row of RSS and ATOM ones. Only the verdict fits; the numbers stay here.

agentmods 80×15 button for cis-verification

Your own site · 80×15
<a href="https://agentmods.dev/skills/jody09-dotcom/constructionx-skills/cis-verification"><img src="https://agentmods.dev/badge/skills/jody09-dotcom/constructionx-skills/cis-verification.svg" alt="Reviewed on agentmods" width="80" height="20"></a>
Per session 89 Skills are progressive disclosure: only the name and description are preloaded; the body loads when the skill is used.
When invoked 1,515 The whole file, excluding the scripts and references it only reads on demand.
Security scan A 0 findings. A grade says what 26 rules found in the file — not that it is safe.
Origin original No closer match found in the catalogue.
Token cost

What it costs to keep this loaded

Counted locally with the o200k_base tokenizer, which is exact for GPT models; Claude uses its own tokenizer and its counts differ. Treat this as one consistent yardstick across the catalogue rather than a bill. Prices are per million input tokens.

ModelPer sessionOnce invoked
Fable 5.1 $0.00089 $0.01515
Opus 5 $0.00044 $0.00758
Sonnet 5 $0.00018 $0.00303
Haiku 4.5 $0.00009 $0.00152

Measured 9d ago against content hash 333c67ccc725, method: parsed. Prices are Anthropic first-party input rates as of 2026-09-09, from the pricing page.

Security

Grade A, and why

cis-verification scanned grade A with 0 findings against 26 rules in 11 categories — prompt injection, anti-refusal, data exfiltration, privilege escalation, supply chain, agent snooping, system-prompt leakage, SSRF and excessive agency — measured 9d ago.

A static scan of the body, not an audit. Every finding is printed with the line that produced it so you can judge whether it matters here. A mod is markdown that instructs an agent; that is exactly why what it instructs is worth reading.

Nothing flagged

None of the 26 patterns this scan looks for appear in this file: no shell pipes, no recursive deletes, no credential paths, no hidden text, no instruction-override or anti-refusal phrasing, no agent-config snooping. That is not a guarantee, it is the absence of the things that are checkable.

skills/cis-verification/SKILL.md · 141 lines

How it starts

The opening of the file, as written. The whole thing — 141 lines — stays where its author put it; the contents beside it link to each section on GitHub.

CIS Verification

This skill walks a UK main contractor through the Construction Industry Scheme (CIS) subcontractor verification process and calculates the correct CIS deduction from a payment. Not tax advice. Verify all rates and deductions with a qualified accountant before making payments.

The skill generates the text the user pastes into the HMRC CIS online portal. It does NOT call HMRC APIs and does NOT submit anything on the user's behalf.

When to Use

  • Onboarding a new subbie before first payment
  • Pre-payment check on an existing subbie (verification expires after 2 tax years of inactivity)
  • Working out the deduction on an invoice that includes labour and materials
  • Preparing the monthly CIS300 return
  • Explaining CIS to a subbie or subcontractor firm

Workflow

Phase 1, gather inputs.

Ask the user for the following:

  • Subcontractor legal name (company name or sole trader name)
  • Trading name if different
  • Unique Taxpayer Reference (UTR), 10 digits
  • For sole traders: National Insurance number (NI)
  • For companies: company registration number (CRN)
  • For partnerships: partnership UTR plus any partner names/UTRs
  • Payment amount on the invoice (gross, inclusive of VAT if applicable)
  • Materials portion of the invoice (direct cost of materials supplied)
  • VAT amount on the invoice (if VAT-registered subbie)
  • CITB levy (if shown separately)

Phase 2, guide through HMRC online verification.

Produce a short paste-ready text block the user copies into the HMRC CIS online portal (https://www.tax.service.gov.uk/gg/sign-in?continue=/construction-industry-scheme-online). Include:

  • Subbie name
  • UTR
  • NI or CRN (as applicable)

Instruct the user that HMRC will return a verification number and a rate (0%, 20%, or 30%). The user enters the verification number back into the skill to continue.

Phase 3, apply rate logic.

Refer to references/hmrc-cis-rules.md for the rate decision tree.

  • 0% (Gross Payment Status): Subbie holds Gross Payment Status with HMRC. No deduction. Still verify; HMRC may return a different rate than expected if the subbie's status has changed.
  • 20% (Standard Rate): Subbie is verified and registered for CIS. Deduct 20% from the labour portion.
  • 30% (Higher Rate): Subbie is not verified, or not registered for CIS, or HMRC cannot confirm the details. Deduct 30% from the labour portion.

Read the full file on GitHub · 141 lines

Files

What ships with it

1 file beside SKILL.md in the same directory: the scripts, references and assets a skill reads on demand. Not counted in the per-session cost; read them before you install if any of them is executable.

Changes

What this file has done since we first saw it

Hashed on every crawl. A supply-chain change to an agent config is a question of when, not whether, so the history is kept rather than the latest state alone.

  1. 9d ago First seen · 141 lines · 89 tokens per session scan A 333c67ccc725

Subscribe to this mod's changes

cis-verification is a skill published in the GitHub repository Jody09-dotcom/constructionx-skills (1 stars, last pushed 4mo ago), licensed MIT. It adds 89 tokens to every session and 1,515 once invoked, about $0.0004 per session on Opus 5. A static security scan graded it A with 0 findings. No closer match exists in the catalogue, so it is treated as the original; first seen 2026-08-31.

Related

Other skills, from other repositories

fiscaliste

Fiscaliste IA pour la fiscalité personnelle des particuliers français : optimisation et déclaration de l'impôt sur le revenu, IFI, revenus du capital, revenus fonciers, equity salarial, crypto-actifs et PER. Couvre le calcul de l'IR (barème, quotient familial, décote, PAS, CEHR, revenus exceptionnels), la déclaration…

romainsimon/paperasse · 302 tokens

commissaire-aux-comptes

Commissaire aux comptes IA pour l'audit des comptes annuels d'entreprises françaises. Applique la démarche NEP en 7 phases : prise de connaissance, contrôle du FEC, vérification du bilan, du compte de résultat, de la balance, de la liasse fiscale, et contrôles transversaux. Émet une opinion motivée sur la fiabilité…

romainsimon/paperasse · 123 tokens

controleur-fiscal

Inspecteur des finances publiques IA. Simule un contrôle fiscal DGFIP complet sur les comptes d'une entreprise française (SASU, EURL, SAS, SARL). Analyse le FEC, la liasse fiscale, les charges déduites, le compte courant d'associé, la TVA, l'IS selon 8 axes de vérification. Identifie les chefs de redressement…

romainsimon/paperasse · 136 tokens

agb-bei-kreditvertraegen-verbraucherdarlehen

Für AGB bei Kreditverträgen Verbraucherdarlehen: ordnet Norm, Beweislast und Gegenargument; Ergebnis: Prüfprodukt mit Risiko und nächstem Schritt.

Klotzkette/claude-fuer-deutsches-recht · 49 tokens

agb-in-kapitalanlagen-effektenhandel

Für AGB in Kapitalanlagen Effektenhandel: ordnet Norm, Beweislast und Gegenargument; Ergebnis: Prüfprodukt mit Risiko und nächstem Schritt.

Klotzkette/claude-fuer-deutsches-recht · 41 tokens

mahngebuehren-und-zinsanpassung-agb

Für Mahngebühren und Zinsanpassung AGB: ordnet Norm, Beweislast und Gegenargument; Ergebnis: Berechnungstabelle mit Annahmen und Kontrollfragen.

Klotzkette/claude-fuer-deutsches-recht · 53 tokens