Tax MCPPricing · Docs · Roadmap & feedback

Tax compute that refuses to guess.

For product teams building tax workflows inside a published supported envelope. Tax MCP computes when the case is modeled, returns a deterministic unsupported or needs_review decline when it is not, and makes billing and retry behavior explicit. No LLM in the loop — same input, same output, every time; primary-source-backed, reproducible, auditable.

Read the supported envelopeRun the first safe call

Ready to build? to create an API key.

Deterministic, not generative

No model in the loop — a table-driven, §6694-disciplined engine, not an LLM. Every figure is primary-source-backed and carries its own derivation; ambiguous cases decline with a reason instead of a wrong-but-plausible guess. Reproducible and auditable, with no per-call model cost.

Idempotent billing

Send an Idempotency-Key and retries replay the byte-identical response, billed exactly once. Quota and per-minute rate limits fail closed.

Coverage-bounded by design

Supported today: selected federal, CA, NY, NYC, reconcile, what-if, and review-packet paths with a machine-readable envelope before any taxpayer payload. Some paths compute only with caller/preparer affirmations; unsupported facts decline deterministically or return needs_review — see the supported-vs-not-modeled reference.

What's in the supported envelope

The boundary is published, not discovered at runtime. Anything on the right returns a deterministic 200 decline (a reason + next_action), never a wrong-but-plausible number. Machine-readable at /api/mcp/tax-capabilities.

Supported today

  • Federal 1040 — ordinary tax, NIIT (8960), Additional Medicare (8959), preferential LTCG / QDIV bands
  • Standard or itemized deduction (Schedule A: SALT with OBBBA cap + mortgage interest, greater-of)
  • Selected credits, Schedule C/E, pension, Social Security, capital-loss carryover, Schedule D / 8949, and §1256 paths when documented facts and affirmations are supplied
  • CA 540 + selected NY / NYC 2025 compute paths
  • Non-mutating CA reconcile against a filed return

Declines deterministically

  • Full-return preparation or filing; broad credits / Schedule A / Form 1116 beyond the documented slices
  • Missing or contradictory affirmations; over-threshold QBI; broad K-1, partnership, and S-corp income
  • Dirty, noncovered, unsupported, or source-conflicted Schedule D / Form 8949 facts
  • States beyond CA / NY; unmodeled years; broad document upload-to-compute workflows

Needs review

  • Reconcile returns needs_review when computed source facts and filed-return oracles differ
  • Source documents are evidence for review, not promoted into compute without caller assertions
  • Public one-click marketplace connectors remain planned, not shipped

Roadmap, in order

A few near-term themes below. The full complete-tax-engine roadmap — every feature, with shipped / certifying / planned status — lives on the roadmap page(a proposed working order, independently reviewed before it's locked). If you think something should move up, tell us on feedbackand we'll use it to reorder the next slice.

1 · Held legal finish

legal_notice {ref, version, text} + /terms

Finalize the legal notice shape and publish binding terms only after the founder legal facts are cleared.

2 · Roadmap input

Support / feedback / changelog

Give users a direct way to tell us what is blocking adoption, what should move up, and what should be clarified next.

3 · First-call onboarding

Quickstart + checklist

Make the first successful call easier with clearer setup, decline interpretation, and next-step guidance.

4 · Document workflow

Upload documents → JSON envelopes

Let users upload source documents and receive a structured JSON envelope they can inspect, store, and pass downstream.

5 · Broader trust surfaces

Docs, marketplace, deeper envelope

Expand the docs, marketplace copy, and supported envelope only after the higher-priority trust and adoption gaps are addressed.

Influence the roadmapSend feedback

Get started

  1. Sign in and create an API key from your dashboard — shown once, scoped to your account.
  2. Authenticate by sending the key as a Bearer token on every request.
  3. Compute: POST a JSON profile and get computed tax within the supported envelope, or a deterministic decline with a reason and next action.
Quickstart & API referenceSee pricing

Deterministic, §6694-disciplined US tax compute. An HTTP 200 is billable whether the engine computed a result or honestly declined. Full spec: /api/openapi.json.
Roadmap · Changelog · Status · Feedback · support@tax-mcp.com