US Taxability Matrix Guide — connector documentation

MCP endpoint: https://us-taxability-guide.connectorbay.com/mcp
REST API: POST https://us-taxability-guide.connectorbay.com/v1/tools/{tool_name}, described by the OpenAPI 3.1 spec at https://us-taxability-guide.connectorbay.com/openapi.json
Transport: Streamable HTTP, stateless, MCP specification 2025-06-18 or later
Authentication: none required. An optional Authorization: Bearer <key> raises rate limits.
Health: https://us-taxability-guide.connectorbay.com/health · Tool schemas: https://us-taxability-guide.connectorbay.com/tools.json
Publisher: Unify Dynamics LLC · connectorbay.com/us-taxability-guide · agent@connectorbay.com

What US Taxability Matrix Guide is for

A guide to the State Taxability Matrix published by the Streamlined Sales Tax Governing Board: what the page says the matrix identifies (the definitions and tax administration practices adopted by the Governing Board that each member state must follow), how its Library of Definitions is divided (Section A administrative definitions, Section B sales tax holidays, Section C product definitions), and where the official online viewers, the updates library and the user guide are. It lists the Streamlined member states the matrix relates to (from the same publisher's exemptions page), quotes the liability-relief wording for sellers who relied on the prior version of the matrix and computes the date until which that wording gives relief after a change notice, and describes the path the sources give for confirming how a state treats a product. It does NOT return any state's taxability of any product: the matrix viewers were not read and no programmatic access to the matrix data was verified, so this stays a guide. Every answer names its source, the date read and a verification level. General information only, not tax advice.

Ask your assistant things like:

"What is the Streamlined taxability matrix and how is it organised?"
"Where can I look up how a Streamlined member state treats a product?"
"Which states does the Streamlined taxability matrix cover?"
"A state notified a change to its matrix on 15 September 2026: until when is a seller relieved of liability for relying on the prior version?"
"What is the path to confirm whether a member state taxes a product before charging tax?"

What it does

explain_matrix: Describe what the Streamlined taxability matrix identifies and how its Library of Definitions and Tax Administration Practices are organised, quoting the SSTGB page.
viewer_links: Return the official viewer, updates library and user guide links of the taxability matrix as printed on the SSTGB page.
member_states: List the 24 Streamlined Sales Tax member states (23 full and Tennessee associate) that the matrix's definitions relate to.
liability_relief_rule: Quote the seller liability-relief wording and compute the first day of the calendar month at least 30 days after a change notice, the date until which the wording gives relief.
how_to_confirm: Describe the path the sources give for confirming how a member state treats a product before charging tax, each step tagged with its source.

Data sources

Reference data from official sources (streamlinedsalestax.org); every answer states its source, date and validity period.

What it is not

US Taxability Matrix Guide is independent; not affiliated with, endorsed by or operated by any government body, central bank, standards body or scheme operator. Names of rails, schemes and standards are used only to say what a tool works with. It is read-only: it never sends, pays, files or signs anything for you, and it never looks up private individuals.

Not advice. General information only, not legal, tax, accounting or payment advice. US Taxability Matrix Guide is an independent tool: it is not affiliated with, endorsed by or operated by any government body, central bank, standards body or scheme operator. Rates, thresholds and rules change; check the cited official source and confirm with a qualified professional before you rely on a result.

Built for: United States. Languages: English.

Tools

Reference & guides

explain_matrix — Describe what the Streamlined taxability matrix identifies and how its Library of Definitions and Tax Administration Practices are organised, quoting the SSTGB page. Use for "What is the Streamlined taxability matrix and how do I read it?".

viewer_links — Return the official viewer, updates library and user guide links of the taxability matrix as printed on the SSTGB page. Use for "Where can I look up how a Streamlined member state treats a product?".

member_states — List the 24 Streamlined Sales Tax member states (23 full and Tennessee associate) that the matrix's definitions relate to. Use for "Which states does the Streamlined taxability matrix cover?".

liability_relief_rule — Quote the seller liability-relief wording and compute the first day of the calendar month at least 30 days after a change notice, the date until which the wording gives relief. Use for "A state changed how it taxes a product: until when am I relieved of liability if I relied on the old matrix?". Args: notice_date.

how_to_confirm — Describe the path the sources give for confirming how a member state treats a product before charging tax, each step tagged with its source. Use for "What is the path to confirm whether a state taxes a product before I charge tax?".

Conventions

Read-only. Every tool reads public data or computes; nothing is written anywhere and nothing about the user is stored.
Result envelope. ok: true with data, or ok: false with a structured error (bad_input, not_found, upstream_error). degraded lists optional sources that were unreachable.
Rate limits. Free tier 60 tool calls/minute and 300/day per user (keyed on the user identifier supplied by the host agent, else client IP); Pro keys raise this. Over-limit calls return HTTP 429 with Retry-After. initialize and tools/list are never counted.

Support

agent@connectorbay.com · connectorbay.com/us-taxability-guide/support