Pass-through tax rules MCP server

• Registry namecom.passthroughtax/pass-through-tax-rulesverified in the MCP registry

The registry name sits under passthroughtax.com. The registry only lets a publisher use that namespace after proving control of the domain through DNS or HTTP.

• Stateanswerschecked 2026-10-29
• Tools4
• Server calls itselfpass-through-tax-rules
• Server version0.2.0
• Protocol version2025-06-18

On 2026-10-29 the server answered initialize and tools/list without a sign-in. First answer in 144 ms.

• Its tools do every use case we checked: Look up the federal SALT cap for a given filer; Confirm whether a state follows federal bonus depreciation for 2026.
• Checked on 6 of the 7 days it takes to judge reliability.

Said by rules from the measurements above. The likely first call is a model's pick from the tool list; read its description before relying on it.

• INITE MCP scoreafter a weeka score needs 7 daily checks: 6 so far
• What an agent can do with it2 of 2 use cases
• Answeredmeasuring6 of the 7 daily checks it takes to print a share
• Median first answer516 ms
• Space in an agent's context≈ 658 tokensthe definitions of all its tools (4), which an agent carries on every turn
• Tool definitionsA · 100 of 100
• Typed results0 of 4 toolsdeclared outputSchema: results come typed, read once

• Every tool passes all six checks.

A program checks the server once a day: initialize and tools/list, no model. Tokens are the definitions' length at about four characters a token. The grade averages six checks of every tool's name, description, schema and annotations; it says how well the tools are described, not whether they work. The score weighs what was measured and nothing else: answering (25%), doing the product's job (25%), definitions (20%), context (10%), use (10%) and how readily a client connects (10%). A part that was not measured is left out, and a hidden instruction caps the score at 40. The state of vendors' MCP servers: method and numbers →

• ptet_rules

  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.

• salt_cap

  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…

• bonus_conformity

  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.

• coverage

  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.