Opentax

Install

Works with Claude Code, VS Code, Codex, Cursor, Windsurf, Claude Desktop. Read the repository before you give any tool access to your data.

npx agentmarket install connector/invaro-opentax

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Permissions

What this server can do and what it asks for, from its tool list and install config. Checked Oct 25, 2026.

Tools

13 read · 0 write · 0 delete · 2 not yet classified

Secrets

None asked for

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Runs as

Node.js package

Tools (15)

As the server listed them on Oct 25, 2026. Descriptions are the server’s own words; hidden characters are shown as [U+…].

• calculate_business_tax

  Compute US federal BUSINESS-ENTITY tax from the same cited corpus: check-the-box entity classification, Form 1120 corporate income tax (§ 179/168(k)/174A/163(j)/DRD/NOL, § 250, GBC/FTC/BEAT), S-corp entity taxes, corporate estimates, the § 4501 buyback excise, AET and PHC taxes. Individual returns → calculate_tax. Unknown keys are rejected; unmodeled territory refuses loudly with the reason.

• calculate_fiduciary_tax

  Compute US federal income tax for an ESTATE or TRUST (Form 1041): the § 1(e) compressed brackets and § 642(b) exemption. Input is taxable income before the exemption, after the §§ 651/661 distribution deduction. Retained capital gains refuse loudly (§ 1(h) trust breakpoints not modeled). Grantor trusts belong on the grantor's individual return via calculate_tax.

• calculate_tax

  Compute US federal INDIVIDUAL income tax (or balance due if withholding is given) from a content-addressed corpus of cited rules. NEVER estimate tax yourself — call this, and report ONLY numbers returned by oracle calls made with the real facts (never hand-check or approximate a line the oracle can compute: your recalled parameters may be stale). Negative result = refund. Returns the answer, every assumption made, and hashes that let anyone re-verify the full derivation offline. Facts are grouped (filing, income, retirement, credits, …) — fill the groups that apply; unknown keys are rejected, …

• compare_filing_statuses

  Compute the answer under every filing status for the same facts — e.g. to answer 'should we file jointly or separately?'. Statuses that need more facts report their error instead of guessing.

• compute_return

  Compute the COMPLETE Form 1040 bottom-line set in one call — the 17 lines that determine the return (1a, 9, 10, 11, 12e, 15, 16, 17 AMT, 19, 22, 23, 24, 25d, 27a, 28, 32, 33, 34/37), each whole-dollar rounded by the engine. Takes the SAME input as calculate_tax (prefer the documents block: transcribe W-2/1099-R/SSA-1099 boxes and dependent birth dates — SSA-1099s are first-class, box 5 and box 6 are summed for you; the tool derives ages, classifications, Part IV withholding, and penalties deterministically). Never assemble return lines by hand — this tool is the return. TRANSCRIPTION CONVENTIO…

• compute_state_return

  Compose a STATE return's printed-form line set deterministically (2025 IL-1040 / VA 760 / CA 540 / NY IT-201 / PA-40 / NJ-1040 / OH IT 1040 / NC D-400 / GA 500 / MD 502 / MO-1040 / WI Form 1 / MN M1 / SC1040 / AL Form 40 / OR-40 / OK Form 511 / CT-1040 / KS K-40 / AR AR1000F / NM PIT-1 / NE 1040N / ID Form 40 / WV IT-140 / ME 1040ME / HI N-11, RI-1040, MT Form 2, DE PIT-RES, ND-1, VT IN-111) — correct line NUMBERS from the printed forms and whole-dollar rounding, with the state tax computed by the oracle targets internally. DE filing status 4 (married filing combined separate) is TWO returns o…

• determine_dependent

  Determine whether ONE candidate person is the taxpayer's § 152 dependent — qualifying child or qualifying relative, including multiple-support agreements and the divorced-parents release — as a proof-backed yes/no with citations. Feed the result into calculate_tax's credits group (qualifyingChildren / otherDependents).

• explain_rule

  Get a tax rule in full: statutory citation with its verbatim excerpt, validity window, parameters, the formula and applicability guard (the rule IR — rules are data), the rules and facts it depends on, and its content hash. Use to quote and explain the actual law behind an answer. Pass asOf to see only the version in force on that date.

• find_tax_cliffs

  Find exact dollar amounts where one more cent of an input costs MORE than a cent of tax (marginal rate over 100%) — e.g. the EITC investment-income kill switch, CTC phase-out steps. Every probe is a real evaluation.

• is_tipped_occupation

  Determine whether a job is on the Treasury Tipped Occupation list (Treas. Reg. § 1.224-1, final Apr 2026) for the § 224 'no tax on tips' deduction. Fuzzy-matches the job name; returns the official listing (name, TTC code, category) or a definitive 'not listed'.

• list_input_facts

  Discover every input the tax corpus understands: id, type, whether required, and its documented default. Call this if unsure what information to collect from the user.

• lookup_tax_parameter

  Look up the current-law dollar amounts behind a question ('standard deduction', 'CTC phase-out threshold', 'tips deduction cap') with their statutory citations and validity windows. Use this to fact-check ANY tax number before stating it — your training data likely predates the OBBBA.

• search_tax_rules

  Full-text search over the encoded tax-law corpus ('kiddie tax', 'NIIT threshold', 'california renters credit'). Returns matching rules: id, title, statutory citation, effective window, and a verbatim excerpt of the law text. A hit means the engine computes this; zero hits means it is outside the corpus — say so rather than guessing. Follow up with explain_rule for a hit's full formula, or lookup_tax_parameter for its dollar amounts.

• verify_fact

  Fact-check a claimed dollar amount about tax law ('the 2026 MFJ standard deduction is $32,200', 'CTC is $2,000 per child') against the corpus. Returns verified / refuted (with the correct value and citation) / unknown. Never states a verdict it cannot ground.

• verify_tax_claim

  Verify a claimed tax amount (yours, a user's, or another tool's) against the law. Returns verdict 'verified' or 'refuted' with the correct value. Use this as a self-check before presenting any tax number. Put asOf (and target, if any) INSIDE the facts object — e.g. facts: {..., "asOf": "2025-12-31"} — otherwise the claim is checked under today's law.

Signals

Weekly downloads

24

Last release

Jul 23, 2026 (3 months ago)

Last package publish

Jul 24, 2026 (3 months ago)

From the package registry.

Details

Registry name

io.github.Invaro/opentax

Version

0.2.1

Auth

Auth not stated

Packages

npm @invaro/opentax

License

AGPL-3.0

First seen

Oct 24, 2026

Last checked

Oct 24, 2026

Source

Official MCP Registry