OpenAccountants

The only open tax knowledge layer for AI agents where named, licensed accountants stand behind the answers.

Agents can already do the math. None of them can stand behind an answer. Every other tax dataset ships with "not tax advice" and stops there. Here, a named professional with a verified credential reviews the complete Guide for their jurisdiction, publicly, on the record.

The scoreboard

10 of 193 jurisdictions

have a named, licensed Partner on record. The other 183 are open. Claim yours →

Every reviewed Guide carries its reviewer badge — name, credential, review date, public proof:

✅ Accountant-reviewed · Christopher Aryee, CPA (US) · credential verified · 2026-07-04 · 33 corrections, full public diff

1,000+ Guides across 190+ jurisdictions, working with Claude, ChatGPT, Cursor, Windsurf, and any MCP-compatible agent. Every Guide is in exactly one of two states, and the repo greps honestly:

• Source-cited draft — written from primary legislation, every figure cited, not yet professionally reviewed

• Accountant-reviewed — a named, licensed Partner checked the complete Guide; their badge is on it (full roster)

⚠️ General reference only, not advice. Have a qualified professional review outputs before filing, payment, or action. Read the full disclaimer

OpenAccountants provides general tax and accounting reference material for AI-assisted workflows. It is not a law firm, accounting firm, tax preparer, or return-filing service, and its outputs are not tax, legal, accounting, or financial advice. Guides may be incomplete, outdated, or wrong, and are not reviewed for any specific person's facts, elections, deadlines, residency, or local procedures. Always have a qualified professional review outputs before filing, payment, or action. A source-cited draft has not been reviewed by a credentialed accountant.

Related MCP server: mcp-europe-business

What it does

You:    "I'm a freelancer in South Africa. What do I owe?"
          ↓  OA loads za-income-tax, za-provisional-tax
AI:     ITR12 working paper
        Provisional tax schedule (IRP6, Aug + Feb)
        Medical tax credits
        Retirement annuity deduction
        ─────────────────────────────────────────
        Reviewed by Werner Britz CA(SA)
        [Request accountant review →]

Add to your AI → | Browse Guides → | Become a Partner →

Install in 60 seconds

Hosted (1 step, always current): add the OpenAccountants connector to your AI at openaccountants.com/connect, or point any MCP client at:

https://www.openaccountants.com/api/mcp

Local (2 steps, no clone needed): the PyPI package ships with all Guides bundled.

pip install openaccountants-mcp     # or: uvx openaccountants-mcp

{ "mcpServers": { "openaccountants": { "command": "openaccountants-mcp" } } }

Works in Claude Desktop (claude_desktop_config.json), Cursor (.cursor/mcp.json), Claude Code, Windsurf, and any MCP-aware client. Full setup and env vars: mcp/README.md.

Manual (no MCP): download a folder from packages/ and drag the .md files into your AI. Read START-HERE.md for scenarios and what to say.

Partners: the named professionals behind the Guides

The canonical roster lives in PARTNERS.md (and adding yourself to it is step two of Partner onboarding). These licensed practitioners have reviewed Guides for their jurisdictions. Their name appears on every answer the AI gives from a Guide they reviewed, and their reviews are public.

Accountant-reviewed Guides (Tier 1) are served via the MCP server with the Partner's name on every output. Guides in this repo that no Partner has reviewed yet are source-cited drafts (Tier 2).

Licensed accountant? Review a complete Guide for your jurisdiction and your name goes on it, publicly and permanently. Start here.

Two ways to use

This repo is the public record. Every rate, every review, every correction is auditable here, in the open, with git history. The hosted MCP serves the same content plus the live review layer.

Quick start (manual path)

1. Find your jurisdiction

packages/
├── malta/           ← income tax + VAT + SSC + payroll + formation + bookkeeping
├── uk/              ← SA103/SA100 + VAT100 + NIC + CGT
├── germany/         ← Einkommensteuer + UStVA + payroll (fullest package)
├── brazil/          ← IRPF + PIS/COFINS + e-invoice + payroll
├── south-africa/    ← ITR12 + VAT + provisional tax
├── us-federal/      ← 1040 / 1120 / 1065 / 1041 form guides (CPA-reviewed, OBBBA-current)
├── ... 130+ more countries
├── us-ca/           ← Federal Schedule C/SE + California state
├── ... 51 US state packages
├── ca-on/           ← Federal T1/T2125 + Ontario
├── ... 13 Canadian province/territory packages

New here? Read START-HERE.md: scenarios, file lists, what to say to the AI. The full machine-readable inventory of every Guide is index.json.

2. Upload to your AI

• Claude.ai → Create a Project, add files as Project Knowledge

• ChatGPT → Attach files or create a Custom GPT

• Any other AI → Attach or paste the files

3. Go

Help me with my 2025 taxes. Here's my bank statement.
Help me set up a company in Malta.
Run my payroll for this month.
Prepare my annual accounts.
Optimize my tax. What deductions am I missing?
Check my invoice compliance for EU e-invoicing.

The AI asks a few questions, loads the right Guides, and produces a working paper for your accountant.

What's in each package

Special packages: _cross-border/ (37 skills) · _verticals/ (14 industry skills) · _integrations/ (10 platform skills: Xero, QuickBooks, Stripe, Wise, Shopify, and more) · us-federal/ (US federal form guides + machine-readable rates.2025.json / rates.2026.json) · uk/ (structured rates.2025.json, 2025/26, every figure statute-cited)

Coverage

Full accounting suite (13 countries)

Tax + bookkeeping + payroll + formation + financial statements + transfer pricing + tax optimization:

Malta · UK · Germany · Australia · Canada · India · Spain · France · Japan · Netherlands · Portugal · Belgium · United States (CA)

Multi-skill countries (~56 countries)

VAT + income tax + social contributions (and often more):

Argentina, Austria, Belgium, Brazil, Bulgaria, Chile, China, Colombia, Croatia, Cyprus, Czech Republic, Denmark, Estonia, Finland, Greece, Hong Kong, Hungary, Indonesia, Ireland, Israel, Kenya, Latvia, Lithuania, Luxembourg, Malaysia, Mexico, New Zealand, Nigeria, Norway, Pakistan, Panama, Peru, Philippines, Poland, Qatar, Romania, Saudi Arabia, Singapore, Slovakia, Slovenia, South Africa, South Korea, Sweden, Switzerland, Taiwan, UAE, and more.

Crypto tax (22 countries + all 51 US states)

Malta, UK, Germany, France, Australia, Canada, Israel, India, Japan, Spain, Netherlands, Portugal, Italy, Singapore, Brazil, Mexico, Sweden, Belgium, Switzerland, South Korea, New Zealand, and every us-<state> package.

VAT/GST only (65 countries)

Consumption tax classification with local supplier pattern libraries. From Albania to Zimbabwe.

Full coverage breakdown: docs/QUALITY-TIERS.md · Machine-readable: index.json

How the Guides work

The supplier pattern library

Every Guide contains a lookup table of local vendors. When the AI sees "BANK OF VALLETTA" or "DEUTSCHE TELEKOM" or "STRIPE PAYMENTS UK LTD" on your bank statement, it already knows the classification. No guessing.

Three outcomes per transaction

Conservative defaults

When uncertain, the system always assumes MORE tax, never less. Your accountant can override a conservative position. They can't easily undo an aggressive one.

Are you an accountant?

Most Guides are source-cited drafts: written from primary legislation but awaiting a credentialed review. Become a Partner for your jurisdiction, review a complete Guide, and it becomes accountant-reviewed with your name on every answer the AI gives from it. Christopher Aryee's 33-correction OBBBA review is what that looks like in practice.

You don't need GitHub. Just:

1. Apply at openaccountants.com/for-accountants (credentials reviewed in 1–2 business days)

2. Open a Guide in your review queue, check every figure against the sources

3. Approve it or return sourced corrections. Either way your review is on the record

Or: fork, fix a rate against your tax authority's guidance, PR. Your name on the Guide either way.

130+ jurisdictions are still open for a Partner. Claim yours →

Contribute

See CONTRIBUTING.md for the full guide and docs/REPO-LAYOUT.md for which file to edit. Every contributor is credited publicly on the Guide and at openaccountants.com.

Pull requests: contributions are accepted under the Contributor License Agreement (CLA.md).

If this repo saves you one email to your accountant, star it. Stars get jurisdictions reviewed faster.

For developers

Repo structure

openaccountants/
├── index.json             ← Machine-readable inventory of every Guide (start here, agents)
├── packages/              ← Ready-to-use jurisdiction packages
│   ├── malta/ uk/ ...     ← generated from skills/ (don't edit directly)
│   ├── us-federal/        ← HAND-AUTHORED US federal form guides + rates JSONs (edit directly)
│   └── ... 130 countries + 51 US states + 13 Canadian provinces
├── skills/                ← Source files for everything except us-federal
│   ├── foundation/        ← Workflow bases (universal, VAT, payroll, etc.)
│   ├── federal/           ← US federal topical skills
│   ├── international/     ← Country-specific skills
│   ├── cross-border/      ← WHT, PE risk, treaty corridors
│   ├── verticals/         ← Industry-specific
│   └── integrations/      ← Platform export formats
├── workflows/             ← Structured advisor workflow definitions
├── mcp/                   ← The MCP server (also on PyPI as openaccountants-mcp)
├── scripts/
│   ├── build-packages.py  ← Generates packages/ from skills/ (us-federal is protected)
│   ├── build-index.py     ← Generates index.json
│   └── validate-guides.py ← CI validation (runs on every PR)
└── docs/                  ← Layout, quality tiers, coverage, templates

Full layout and "which file do I edit": docs/REPO-LAYOUT.md

Rebuild packages after editing skills

python3 scripts/build-packages.py   # us-federal is never touched
python3 scripts/build-index.py      # refresh index.json

Known limitations

• LLMs hallucinate. These files steer the model; they don't guarantee correct numbers. Always have a qualified professional review before filing.

• Tax law changes. Rates and thresholds go out of date. The repo is a snapshot; openaccountants.com may be ahead of what you cloned. (When a professional catches drift, it lands here as a public correction, like PR #45.)

• Coverage is uneven. 13 countries have the full accounting suite; many jurisdictions have VAT only or partial coverage. Check each country folder's README or index.json.

• Newer domains need more eyes. Bookkeeping, payroll, formation, and financial statements Guides are source-cited drafts with fewer Partner reviews than the core tax Guides.

Disclaimer

OpenAccountants provides general tax and accounting reference material for AI-assisted workflows. It is not a law firm, accounting firm, tax preparer, or return-filing service. Outputs are not tax, legal, accounting, or financial advice, are not reviewed for your specific facts, and must be reviewed by a qualified professional before filing, payment, or action. Using a Guide does not create a client relationship. A source-cited draft has not been reviewed by a credentialed accountant; only an accountant-reviewed Guide carries a Partner's review, and that review is of reference material, not of any specific taxpayer's situation.

The most up-to-date, reviewed version is maintained at openaccountants.com.

Contact

info@openaccountants.com · openaccountants.com

License

Dual-licensed: AGPL-3.0 for open-source use, commercial license for proprietary products.

Contributions are licensed to the project under the Contributor License Agreement. See CONTRIBUTING.md.