NL Tax Agent Skills

Turn scattered Dutch tax paperwork into a reviewable, source-cited workpackfor manual entry in Mijn Belastingdienst.

For employees, homeowners, ZZP'ers and freelancers. Runs in Claude, Claude Code, Codex and ChatGPT, and installs in other agents through the skills CLI.

Install · What's covered · Examples · Privacy

[!IMPORTANT] A preparation aid, not tax advice. The assistant organizes your facts, cites official rules and maps amounts to portal fields. You enter and submit everything in Mijn Belastingdienst; the assistant never logs in, signs or files.

✨ How it works

flowchart LR
    subgraph chat["💬 In the conversation, with the assistant"]
        direction LR
        A["📄 <b>Share</b><br/>jaaropgaaf, mortgage,<br/>bank, ledgers"] --> B["❓ <b>Answer</b><br/>only the missing<br/>questions"]
        B --> C["📋 <b>Review</b><br/>workpack: every amount<br/>with its source"]
        C --> D["🗺️ <b>Field map</b><br/>which value goes<br/>in which field"]
    end
    subgraph portal["🔐 Only you"]
        E["✍️ <b>Enter and submit</b><br/>in Mijn<br/>Belastingdienst"]
    end
    D --> E

• Reads your documents and works out where each amount belongs, using bundled notes that cite the official Dutch rules for that tax year.
• Asks only what's missing, nothing that doesn't change the result.
• Shows its work. Every amount names its source, and open questions stay visible. If you correct something later, the field map is marked stale until it's regenerated, so an old number never reaches the portal.
• Answers rule questions too: "What is the Box 3 heffingsvrij vermogen for 2025?" gets a sourced answer that names the year.

📅 What's covered

Status	Workflow	Year
✅	Annual income-tax return: Box 1 (wages, eigen woning), Box 2, Box 3, deductions, credits, fiscal-partner allocation	2025
✅	Winst uit onderneming for an eenmanszaak / ZZP	2025
✅	Voorlopige aanslag: request, change, review or stopzetten	2026
✅	Rule questions (answers on draft topics say so)	2025 · 2026
🧪	btw-aangifte with KOR screening, and suppletie of a filed period	2025 · 2026
🧪	Opgaaf ICP and OSS / IOSS returns	2025 · 2026
🧪	M-biljet (emigration/immigration year) and C-biljet (nonresident)	20252026 evidence
🧪	Annual return 2026: evidence collection while the year is still open	2026
⛔	VOF / maatschap / CV, BV / DGA, staking, agrarisch, zeevarenden, deceased person	—
⛔	Tax year 2027	—

✅ Reviewed: a full workpack, field map and optional manual-entry checklist. 🧪 Draft: the official sources still await human tax review, so drafts are never called ready to file and the checklist lists only the blockers. ⛔ Not supported: routed to manual review, with the facts collected so far kept for your tax professional. 2027 is blocked until its sources are in.

[!NOTE] Box 3, 2025: the workpack can compare the forfaitair method with werkelijk rendement for your information. It isn't an election: the Belastingdienst runs the binding comparison. The 2026 voorlopige aanslag uses the forfaitair method only.

💼 For ZZP'ers and freelancers

• 2025 profit, step by step: ondernemer tests and urencriterium, KIA, zelfstandigenaftrek, startersaftrek and MKB-winstvrijstelling to your belastbare winst, from your final profit-and-loss statement and balance sheet. You're also reminded of the separate Zvw-bijdrage.
• Not an ondernemer? Income is prepared as resultaat uit overige werkzaamheden after a bron-van-inkomen check. Wet DBA is explained, never decided for you.
• 2026 voorlopige aanslag includes your sourced expected profit.
• btw, ICP and OSS drafts are kept in separate workpacks per period, so no amount is silently merged. Customers' VAT numbers stay aliases; you enter the real ones yourself.

📦 Install

Install the whole plugin, or all of its skills together. The skills share one knowledge pack, so copying a single skill folder or uploading it on its own doesn't work.

In the Claude app or on claude.ai: Plugins (older apps: Customize → Plugins) → Add → Add marketplace → Add from a repository, enter cyanxxy/nl-tax-agent-skills and select Install. The plugin is saved to your account, so it also appears in Claude Code. Use it in the desktop app, where Claude can work in a folder for your workpack and run the specialist reviewer. Claude on the web and mobile loads plugins too, but this one hasn't been verified there yet.

/plugin marketplace add cyanxxy/nl-tax-agent-skills
/plugin install nl-tax-agent-skills@nl-tax-agent-skills-marketplace

codex plugin marketplace add cyanxxy/nl-tax-agent-skills --ref main
codex plugin add nl-tax-agent-skills@nl-tax-agent-skills-local

Then start a new session.

Coming to the ChatGPT Plugins Directory. Once it's listed, open Plugins, install NL Tax Agent Skills, then start a new chat (Chat or Work).

With the open skills CLI (Node.js 22.20 or later), always with every skill together:

npx skills add cyanxxy/nl-tax-agent-skills --skill '*'

Start with nl-tax-intake. These agents also list the background helpers and nl-tax-shared-resources as skills, and the specialist reviewer isn't installed; the workflows run without it.

No shell, Python or setup is needed: the plugin is Markdown and YAML only.

This is the beginning of the README. Read the rest at the original. Read the full README ↗