Tax and accounting guidance verified by licensed accountants across 50+ jurisdictions
Open-source accounting skills covering income tax, VAT, payroll, and compliance. Search tax rules, verify VAT numbers against government registries, check audit exemptions, and get filing deadlines. Accountant-verified for multiple countries and US states.
Try asking Muse: "Tell me what deductions I can claim on my US Schedule C and when my quarterly tax payment is due."
Source: Found in the official MCP Registry (io.github.openaccountants/openaccountants) · First listed September 24, 2026
Each bar is one check, every 15 minutes. Green means it answered. Last checked 4 h ago.
What Muse can see: It does not ask you to sign in, so it cannot see your accounts. It only sees what Muse sends it from your request.
Before it acts: Read what Muse plans to do before you approve it, and remove the app from Muse when you stop using it.
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Not in Muse's Connectors list yet, but Muse can still use it. Copy the request below and paste it into Muse. Muse asks before it shares anything with the app's site. Meta does not review apps used this way, so only use ones you trust. We tested this in the Muse app on September 24, 2026: Muse used an app's link directly this way and returned a live answer.
https://www.openaccountants.com/api/mcpNot in Muse's Connectors list yet. Muse can still use it: its page gives you a request to paste into Muse.
OpenAccountants is a remote MCP server, so any assistant that can add a custom connector by link can use it. Same link, same tools.
In ChatGPT, open Settings, then Connectors (called Apps & Connectors on some accounts).
Under Advanced settings, switch on Developer mode. That is what lets you add a connector by link.
Choose Create, give it a name, paste the link as the MCP server URL, and save. If it needs a sign-in, ChatGPT asks for it here.
Start a chat, open the tools menu, pick the connector, and ask. ChatGPT asks before it runs a tool the first time.
Custom connectors need a paid ChatGPT plan, and on Team, Enterprise and Edu accounts only an admin can add them. Our "Working" label means the server answered us; it cannot tell whether your plan lets you add it. All connectors that work in ChatGPT
In Claude, open Settings, then Connectors.
Choose Add custom connector, give it a name, and paste the link.
If it needs a sign-in, Claude sends you to it. Then turn the connector on in a chat from the tools menu and ask.
Custom connectors are available on paid Claude plans; on Team and Enterprise accounts an admin may need to add them. Our "Working" label means the server answered us; it cannot tell whether your plan lets you add it. All connectors that work in Claude
https://www.openaccountants.com/api/mcpResponse time at the last check: 652ms. Worked in 99.1% of checks over 30 days.
Screened, no issues found
Screening looks for known threats and hidden instructions at the time of the check, and runs again weekly and whenever the tool list changes. It cannot see the server's code, so only connect what you need and review what Muse asks to do. How screening works.
startCall this first for any tax, VAT/GST, payroll or filing question about a country or US state, such as "how much tax will I pay in Spain", "do I need to register for VAT", "when is my tax return due", "is this deductible", "how is a freelancer or a company taxed in Germany", "salesearch_skillsFind or browse skills. With a `query`, finds the skill for a specific tax topic by keyword: a deduction, form, regime or rule such as 'home office deduction', 'Schedule C', 'reverse charge', 'crypto capital gains' or 'Beckham regime'. Without a query, lists the skills for a jurisget_skillOpen a skill by slug (from start, search_skills or search_rules) to answer the user's question. Returns the skill's rules and method, its quality tier, the named accountant where one reviewed it, a `section_index` of sections not inlined, and a provenance footer to keep with the search_rulesLook up tax rates, thresholds and rules in one or many jurisdictions, such as 'VAT rates in MT, IE and DE', 'income tax brackets for 2025' or 'rules mentioning reverse charge'. Returns a bundled markdown rule set plus each jurisdiction's official source (`official_source`). For oget_deadlinesFiling and payment deadlines for a country or US state: 'when is my tax return due', 'when do I file VAT', 'when is the next instalment'. Returns upcoming dates and recurring filing rhythms (monthly VAT, quarterly instalments) from the OpenAccountants tax calendar. Signed-in userlist_jurisdictionsAnswers 'which countries do you cover?' or 'what is there for [country]?'. Returns every jurisdiction with published skills (countries as ISO 2, US states as US-XX, Canadian provinces) with skill counts, accountant-reviewed counts and the named lead accountant where there is one.list_verifiersAnswers 'who reviewed this?' or 'which accountants are behind this?'. Returns the named licensed accountants who have signed off on OpenAccountants jurisdictions, with their credentials and the jurisdictions they cover.get_quoteCall only when the user asks what OpenAccountants charges, requests a quote, or asks whether their current fee is fair. Returns the same published plans, service prices, limits, market exceptions and hourly rate as the website, plus the engagement process and contact details. Matvalidate_vat_numberCheck live whether an EU VAT number is valid and registered, for example before applying a B2B reverse charge, zero-rating an intra-EU sale or onboarding a supplier. Queries the European Commission's VIES registry and returns the verdict plus the registered business name and addrcheck_audit_exemptionAnswers 'does my company need an audit?' for a private limited company in Malta (MT, Article 185(2) micro thresholds) or the UK (GB, small-company thresholds before and after 6 April 2025). A deterministic check of turnover, balance sheet total and average employees. Returns 'execomputeComputes a tax figure with fixed, tested code instead of mental arithmetic. Use this for any figure an engine below covers; never compute that figure yourself. Pass only the facts the user gave: the engine applies the tax rules itself (allowances, standard deductions, bands, capsshare_with_openaccountantsOnly when the user asks: sends their feedback, or their request for a person to check or do the work, to OpenAccountants. Two modes. (1) `note`: an anonymized note about the guidance (a gap, a workaround you needed, or via `skill_slug` a bug in a specific skill). Anonymize hard: https://www.openaccountants.com/api/mcpNot in Muse's Connectors list yet, but Muse can still use it. Paste this into Muse: "Use OpenAccountants to help me. It is a free service with an MCP server at https://www.openaccountants.com/api/mcp. It does not need an API key. Ask me before you share anything with it." Muse asks before it shares anything with the app's site. Meta does not review apps used this way, so only use ones you trust. We tested this in the Muse app on September 24, 2026: Muse used an app's link directly this way and returned a live answer.
At the last check (November 13, 2026, 10:46 UTC) the endpoint was working, answering in 652ms. Over the last 7 days it answered 100% of health checks. It is checked every 15 minutes.
It was screened on September 24, 2026 with the result "screened, no issues found". Screening checks the domain against threat feeds and reads the tools for hidden instructions and requests for passwords or card numbers. It cannot see the server's code, so grant only the access you need.
It exposes 12 tools, including start, search_skills, get_skill, search_rules. For example, you could ask Muse: "Tell me what deductions I can claim on my US Schedule C and when my quarterly tax payment is due."
This listing was added from public sources (Found in the official MCP Registry (io.github.openaccountants/openaccountants)). If you build OpenAccountants, claim it to correct the details and get your badge.
Paste this on your site or README. It always shows the latest check.
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