California Tax Appeals

What California Tax Appeals does

California Tax Appeals MCP server provides access to published opinions from the California Office of Tax Appeals (OTA). The dataset covers 4,254 issued opinions from 2018–2026, including precedential and nonprecedential decisions in Franchise and Income Tax and Business Tax categories.

The server is intended for research in the ⚖️ Legal category. It can help an agent locate decisions involving subjects such as residency or innocent spouse issues, search for OTA listing entries associated with a statute citation, and inspect a particular opinion by its OTA citation.

How it works

The service uses a citation-indexed dataset built from OTA opinion listing pages. Because OTA presents its tables as static HTML rather than exposing a JSON search service, the search operation works against indexed listing metadata. That metadata includes the opinion title and OTA’s one-line Issues tag.

A search returns identifying and classification information, including the OTA citation, title, issue date, tax category, precedential status, and Issues tag. Results are ordered with the most recent opinions first. Searches accept topic terms such as “residency” or statute references such as “17014.”

A separate lookup operation fetches an individual opinion PDF from OTA and extracts its text. The response includes the full text when extraction succeeds, the exact issue date, OTA’s internal case number, tax category, precedential status, and statute citations detected in the document. Citation extraction is best effort and covers references such as the Revenue and Taxation Code, California Code of Regulations, and Internal Revenue Code.

Setup and configuration

California Tax Appeals MCP server can be connected through the hosted Pipeworx endpoint or run locally as a stdio package. The hosted MCP URL is https://gateway.pipeworx.io/california-tax-appeals/mcp; the local package is @pipeworx/mcp-california-tax-appeals, launched with npx -y.

The hosted endpoint requires no signup or API key for these public opinion reads. It also exposes Pipeworx shared meta-tools in addition to the pack’s two tools. A local stdio connection exposes only the California Tax Appeals tools and does not provide the gateway’s shared routing tools. The same operations can also be called over HTTP, including with a POST request to the tool endpoint.

Tools and capabilities

• ca_ota_search(query, category?, precedential_only?, limit?) searches opinion listing metadata by topic or statute citation.
• ca_ota_opinion_lookup(cite) retrieves one opinion using its OTA citation and returns its extracted text and metadata.
• Lookup accepts a citation with the usual trailing precedential marker omitted; the server tries both forms. Other suffixes, such as SCP, must be supplied exactly.
• Results distinguish OTA citations from the eight-digit docket-style OTA Case No. found inside some PDFs.

Limitations and notes

Search does not inspect full opinion text. A statute mentioned only in the body of an opinion, and absent from its title or Issues tag, will not be found through ca_ota_search; identify the opinion first and use ca_ota_opinion_lookup when possible.

California Tax Appeals MCP server depends on OTA’s published listing pages and individual PDFs. A transport or source mismatch produces an error rather than silently reporting that an opinion is missing. If a PDF is available but contains no extractable text, the lookup can return full_text: null with a warning while retaining the available listing metadata.

The indexed data is baked from OTA pages and must be regenerated periodically to include newly issued decisions. The package is an independent, unofficial integration and is not affiliated with, endorsed by, or published by OTA.