Koskamo

Pass-through Tax Rules MCP

An MCP server providing tax-year-dated rules for state pass-through entity taxes (PTET), the federal SALT cap, and bonus-depreciation conformity. It allows users to query specific states and years, citing statutes or revenue-department pages for answers.

Visit Pass-through Tax Rules

Endpoint and access

No sign-in to connect and list tools. Individual tools may still need a vendor account, credentials, or permissions; check the documented prerequisites.

Pass-through Tax Rules MCP logo, by Pass-through Tax RulesVendor evidenceStreamable HTTPNo sign-inEndpoint checked 2026-11-01Operated by Pass-through Tax Rules
MCP endpoint (Streamable HTTP)
https://passthroughtax.com/api/mcp
Vendor documentation

What you can do with it

  • Query California's 2026 pass-through entity tax rate and election deadline
  • Calculate the federal SALT cap for a single filer with specific income
  • Check if Georgia follows federal bonus depreciation for 2026

Source and maintenance

Vendor evidenceRegistry 0.2.0
mcp-registry: com.passthroughtax/pass-through-tax-rules@0.2.0Project website

Protocol and capabilities

Server
pass-through-tax-rules 0.2.0
MCP protocol
2025-06-18
Tools
4 advertised
Resources
Not advertised
Resource templates
Not advertised
Prompts
Not advertised
Server-advertised capabilities
{
  "tools": {
    "listChanged": true
  }
}

Server-provided instructions

Untrusted server output shown for inspection. It is not Koskamo guidance and is excluded from knowledge search.

Deterministic cited rules for US pass-through entity tax, the federal SALT cap, and bonus-depreciation conformity. Answers are informational, not tax advice. If a tool returns not_covered or unverified, do not fill the gap from memory.

Tools

4 advertised

ptet_rules — Pass-through entity tax
Advertised by the server during the last successful anonymous check.
Advertised read-only

Elective pass-through entity tax for one state and tax year: eligibility, who elects, deadline, rate, owner credit or exclusion, estimates, and sunset. Returns not_covered when this server has no file. Informational, not tax advice.

ptet_rules input schema
{
  "type": "object",
  "$schema": "https://json-schema.org/draft/2020-12/schema",
  "required": [
    "state",
    "tax_year"
  ],
  "properties": {
    "state": {
      "type": "string",
      "description": "Postal code or full state name. The District of Columbia is DC. New York City is NYC."
    },
    "tax_year": {
      "type": [
        "number",
        "string"
      ],
      "description": "Tax year, such as 2026. Files are tax-year specific."
    }
  }
}
ptet_rules annotations
{
  "readOnlyHint": true,
  "openWorldHint": false,
  "idempotentHint": true,
  "destructiveHint": false
}
salt_cap — Federal SALT cap
Advertised by the server during the last successful anonymous check.
Advertised read-only

Compute the federal SALT deduction cap under 26 USC 164(b)(6) and (b)(7) for a tax year, filing status, and modified adjusted gross income. Returns the cap and the steps, not the deduction. Years before 2018 are not_covered. MAGI is used to compute and is not written to the usage log.

salt_cap input schema
{
  "type": "object",
  "$schema": "https://json-schema.org/draft/2020-12/schema",
  "required": [
    "tax_year",
    "filing_status",
    "magi"
  ],
  "properties": {
    "magi": {
      "type": [
        "number",
        "string"
      ],
      "description": "Modified adjusted gross income: AGI plus IRC 911, 931, and 933 exclusions. Integer or decimal string, at most 8 decimal places."
    },
    "tax_year": {
      "type": [
        "number",
        "string"
      ],
      "description": "Tax year. 2018 through 2024 use the prior flat cap. 2025 and later use section 164(b)(7)."
    },
    "filing_status": {
      "type": "string",
      "description": "single, married_filing_jointly, married_filing_separately, head_of_household, or qualifying_surviving_spouse. Aliases: mfj, mfs, hoh, qss."
    }
  }
}
salt_cap annotations
{
  "readOnlyHint": true,
  "openWorldHint": false,
  "idempotentHint": true,
  "destructiveHint": false
}
bonus_conformity — Bonus depreciation conformity
Advertised by the server during the last successful anonymous check.
Advertised read-only

Whether a state conforms to IRC 168(k) bonus depreciation and IRC 179 for a tax year, its IRC conformity date, and the add-back or subtraction in plain terms. Unverified fields are null. Unknown states and years are not_covered.

bonus_conformity input schema
{
  "type": "object",
  "$schema": "https://json-schema.org/draft/2020-12/schema",
  "required": [
    "state",
    "tax_year"
  ],
  "properties": {
    "state": {
      "type": "string",
      "description": "Postal code or full state name. The District of Columbia is DC. New York City is NYC."
    },
    "tax_year": {
      "type": [
        "number",
        "string"
      ],
      "description": "Tax year, such as 2026. Files are tax-year specific."
    }
  }
}
bonus_conformity annotations
{
  "readOnlyHint": true,
  "openWorldHint": false,
  "idempotentHint": true,
  "destructiveHint": false
}
coverage — Coverage
Advertised by the server during the last successful anonymous check.
Advertised read-only

List jurisdictions and tax years in this dataset. elective_ptet_2026 counts only 2026 files with an elective PTET. no_elective_ptet_2026 and not_effective_2026 are separate and are not PTET states for 2026.

coverage input schema
{
  "type": "object",
  "$schema": "https://json-schema.org/draft/2020-12/schema",
  "properties": {}
}
coverage annotations
{
  "readOnlyHint": true,
  "openWorldHint": false,
  "idempotentHint": true,
  "destructiveHint": false
}

Prompts

Not advertised

No prompt definitions available.

Resources

Not advertised

No resource definitions available.

30-day availability

Aggregated from read-only remote checks; this is not a tool-execution or security guarantee.

Successful checks
1 of 1 (100%)
Average latency
499 ms
95th percentile latency
499 ms

Maintenance history

Public check and source-refresh events. Editorial and ownership records remain private.

  • · probe · passed · 499 ms · metadata changed · 4 tool(s)

Connect from your client

Each snippet registers the same endpoint; pick the client you use.

This server is operated by the named third party. Listing and endpoint checks are not an endorsement or a security audit. Review the operator's permissions, terms, and data handling before connecting. How listings are checked and corrected.

Claude Code

Run this once in a terminal. It registers the remote server. Use --scope project to write .mcp.json for the repo.
Claude Code configuration
claude mcp add --transport http pass-through-tax-rules-mcp https://passthroughtax.com/api/mcp

Codex

Run this once. Codex stores MCP servers in ~/.codex/config.toml (or .codex/config.toml in a trusted project).
Codex configuration
codex mcp add pass-through-tax-rules-mcp --url https://passthroughtax.com/api/mcp

Cursor

Merge this server into .cursor/mcp.json in your project, then enable pass-through-tax-rules-mcp in your MCP settings.
Cursor configuration
{
  "mcpServers": {
    "pass-through-tax-rules-mcp": {
      "url": "https://passthroughtax.com/api/mcp"
    }
  }
}

Cline

Merge this into cline_mcp_settings.json (Cline → MCP Servers → Configure).
Cline configuration
{
  "mcpServers": {
    "pass-through-tax-rules-mcp": {
      "type": "streamableHttp",
      "url": "https://passthroughtax.com/api/mcp",
      "disabled": false
    }
  }
}

VS Code

Merge this server into .vscode/mcp.json. Use MCP: List Servers to start pass-through-tax-rules-mcp and inspect its tools.
VS Code configuration
{
  "servers": {
    "pass-through-tax-rules-mcp": {
      "type": "http",
      "url": "https://passthroughtax.com/api/mcp"
    }
  }
}

Gemini CLI

Run this once. It writes .gemini/settings.json in the current project; pass --scope user for ~/.gemini/settings.json.
Gemini CLI configuration
gemini mcp add --transport http pass-through-tax-rules-mcp https://passthroughtax.com/api/mcp

Claude Desktop

Merge this into claude_desktop_config.json (macOS: ~/Library/Application Support/Claude/, Windows: %APPDATA%\Claude\), then restart Claude Desktop.
Claude Desktop configuration
{
  "mcpServers": {
    "pass-through-tax-rules-mcp": {
      "url": "https://passthroughtax.com/api/mcp"
    }
  }
}

Windsurf

Merge this into ~/.codeium/windsurf/mcp_config.json, then refresh MCP in Cascade. Windsurf remote servers use serverUrl, not url.
Windsurf configuration
{
  "mcpServers": {
    "pass-through-tax-rules-mcp": {
      "serverUrl": "https://passthroughtax.com/api/mcp"
    }
  }
}

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