A workflow for preparing Dutch personal or business income-tax filings. It organizes information into the Netherlands’ three tax boxes and checks the figures against supporting documents and official tax rules.

Use it to gather income, household, property, investment, business, and prior-year information. It helps verify rates, thresholds, deadlines, and formal requirements on the Dutch Tax Administration website.

It helps find missing evidence, inconsistent amounts, large changes from earlier years, and important filing details. A qualified Dutch tax professional must review the result.

ib-aangifte — Command for Claude Code by johnhout

Install

Getting it into your agent

It runs from inside its repository, so the clone comes first — what it calls does not travel with the file alone.

Clone the repo

git clone --depth 1 https://github.com/johnhout/knowledge-work-belastingzaken

agentmods

npx agentmods add commands/johnhout/knowledge-work-belastingzaken/ib-aangifte

Made for: Claude Code.

Or install belastingadviseur, the plugin that ships this one along with the rest of its 8 skills, 8 commands, 5 MCP servers.

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.

README.md

[![agentmods](https://agentmods.dev/badge/commands/johnhout/knowledge-work-belastingzaken/ib-aangifte/github.svg)](https://agentmods.dev/commands/johnhout/knowledge-work-belastingzaken/ib-aangifte)

Your own site

<a href="https://agentmods.dev/commands/johnhout/knowledge-work-belastingzaken/ib-aangifte"><img src="https://agentmods.dev/badge/commands/johnhout/knowledge-work-belastingzaken/ib-aangifte/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.

Your own site · 80×15

<a href="https://agentmods.dev/commands/johnhout/knowledge-work-belastingzaken/ib-aangifte"><img src="https://agentmods.dev/badge/commands/johnhout/knowledge-work-belastingzaken/ib-aangifte.svg" alt="Reviewed on agentmods" width="80" height="20"></a>

Per session 6 Only the description is in the session, so the agent can decide to use it. The body loads when it is invoked.

When invoked 448 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.

Model	Per session	Once invoked
Fable 5.1	$0.00006	$0.00448
Opus 5	$0.00003	$0.00224
Sonnet 5	$0.00001	$0.00090
Haiku 4.5	$0.00001	$0.00045

Measured 10d ago against content hash de05d507e989, method: parsed. Prices are Anthropic first-party input rates as of 2026-09-09, from the pricing page.

Security

Grade A, and why

ib-aangifte 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 10d 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.

commands/ib-aangifte.md · 59 lines

What it actually says

IB Aangifte / Income Tax Filing

If placeholders are unclear, see CONNECTORS.md.

Important / Belangrijk: This workflow support is not legal or fiscal advice. Require review by a qualified Dutch tax professional.

Prepare Dutch income tax workflow for individuals and entrepreneurs (where applicable), including box-based checks.

Usage

/belastingadviseur:ib-aangifte <belastingjaar> [profieltype]

Workflow

Intake IB context:

Household situation, income sources, business income relevance
Prior-year carryforwards and known open issues

Structure by box:

Box 1: work/home and taxable income components
Box 2: substantial interest context where relevant
Box 3: assets/liabilities and evidence requirements

Gather support:

Statements, annual overviews, expense support, prior assessments
Reconcile user-provided figures against source evidence

Apply checks and controls:

Completeness checks per box
Consistency checks against prior periods
Material variance flags and data quality exceptions

Official-source verification:

Verify thresholds, rates, deadlines, and formal criteria on belastingdienst.nl
Verify legal basis references on wetten.overheid.nl
Include URL and retrieval date for each rule-dependent claim

Fallback behavior:

If ~~boekhouding or ~~data warehouse is not connected, continue with manual evidence and mark assumptions
If a rule cannot be verified officially, mark as unverified and require professional confirmation

Required Output Format (Use Exactly)

Context / Context
Assumptions / Aannames
Required Documents / Benodigde stukken
Step-by-step / Stappenplan
Checks & Risks / Controles en risico's
Next Actions / Volgende acties
Sources (official) / Bronnen (officieel)
Professional Review Disclaimer / Disclaimer deskundige beoordeling

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.

10d ago First seen · 59 lines · 6 tokens per session scan A de05d507e989

Subscribe to this mod's changes

ib-aangifte is a command published in the GitHub repository johnhout/knowledge-work-belastingzaken (6 stars, last pushed 6mo ago), licensed MIT. It adds 6 tokens to every session and 448 once invoked, about $0.0000 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.

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