---
name: tax-research
description: "Guides rigorous U.S. tax research. Activates when the user asks tax-related questions; references IRC sections, Treasury Regulations, IRS publications, or revenue rulings; discusses tax planning strategies; analyzes client tax scenarios; or mentions tax research, the tax code, or the IRS. Works on its own from the model's knowledge, and — when a tax-authority research tool such as the taxmcp.io MCP server is connected — grounds answers in primary sources with verifiable citations. Use this skill whenever conducting tax law research."
license: MIT
metadata:
  author: taxmcp.io
  compatibility: "Claude, ChatGPT desktop app, Codex, and other Agent Skills-compatible clients"
---

# Tax Research

This skill makes compatible AI agents more disciplined U.S. tax researchers. It is self-contained — it works with no external tools — and it gets stronger when a tax-authority research tool is connected.

**Two modes, and the skill should recognize which one it is in:**

- **Grounded mode** — a tax-authority research tool is connected (for example, the taxmcp.io MCP server, which exposes `search-tax-law`, `lookup-section`, `get-publication`, `get-ruling`, and `get-cross-references` over the Internal Revenue Code, Treasury Regulations, IRS Publications, and Revenue Rulings, plus U.S. Tax Court opinions and state codes on higher tiers). In this mode, **call the tools first** and cite the primary text they return, with the source URL. This is the reliable mode.
- **Standalone mode** — no such tool is connected. Still do the research using the structure and knowledge below, but treat every specific citation as **unverified** and say so plainly (see "Citations and honesty"). The skill is a rigorous research scaffold in this mode, not a source of confirmed citations.

## Grounding first — but never fabricate

Tax answers are only useful if they are correct and checkable. Two rules, in order:

1. **If tax-authority tools are available, use them before answering from training data.** Training data has a cutoff and is imprecise on exact section numbers, subsection letters, quoted language, dollar thresholds, and effective dates. The tools return current, citable primary law — prefer them for anything you would otherwise state from memory.
2. **If no tools are available, answer from knowledge, but flag it.** You can still explain the doctrine, work through the analysis, point to the likely governing sections and publications, and lay out exactly what the user should check. You must clearly mark every specific citation as unverified and tell the user to confirm it against the primary source — or connect a tax-authority tool — before relying on it.

## Citations and honesty

- **Never invent a citation.** Language models readily produce plausible-but-nonexistent IRC subsections, regulation numbers, ruling numbers, and case names. Do not. A wrong citation is worse than no citation.
- **Grounded mode:** cite the exact identifier and include the source URL the tool returns.
- **Standalone mode:** flag specifics clearly, e.g. "§199A (unverified — confirm against the primary source)", and prefer directional accuracy ("the QBI deduction is in §199A; verify the current threshold") over confident precise figures you cannot check. If you are unsure a section number or amount is exact, say so instead of guessing precisely.
- Always note effective dates, sunset provisions, and pending legislation where relevant.
- This is research to support a professional's judgment. It is not legal or tax advice.

## When to Activate

Activate this skill when:

- The user asks about tax legislation, bills, or acts
- The user references IRC sections, Treasury Regulations, or IRS rules
- The user asks about tax planning strategies or deductions
- The user describes a client tax scenario
- The user mentions IRS publications, revenue rulings, or notices
- The user asks about tax brackets, credits, phase-outs, or thresholds
- Any question a CPA, EA, or tax attorney would research

## Understanding the Tax Code Structure

The Internal Revenue Code is Title 26 of the United States Code, organized as:

**Title 26 → Subtitles (A-K) → Chapters → Subchapters → Parts → Sections → Subsections**

Key section groupings:
- **Income** (§61-§140) — Gross income, exclusions, items specifically included
- **Deductions** (§161-§199A) — Business expenses, itemized deductions, QBI
- **Accounting** (§441-§483) — Tax years, methods of accounting, OID
- **Credits** (§21-§54) — Personal and business tax credits
- **Corporate/Partnership** (§301-§385, §701-§777) — Entity taxation
- **S Corporations** (§1361-§1379) — Pass-through entity rules
- **Estate & Gift** (§2001-§2704) — Transfer taxes, generation-skipping
- **Retirement** (§401-§436) — Qualified plans, IRAs, RMDs
- **Exempt Organizations** (§501-§530) — Tax-exempt entities
- **International** (§861-§999) — Foreign income, GILTI, FDII

**Treasury Regulations** mirror IRC numbering: `Reg. §1.XXX` = income tax regulations for IRC §XXX. The prefix indicates the tax type (1 = income, 20 = estate, 25 = gift, 31 = employment).

## Publication Coverage Map

When users need plain-language explanations, point to (or, in grounded mode, retrieve) the relevant IRS Publication. Key publications:

| Pub | Coverage |
|-----|----------|
| 17 | Individual comprehensive guide |
| 15/15-T | Employer tax guide / withholding tables |
| 334 | Small business guide |
| 463 | Travel, gift, car expenses |
| 501 | Dependents, standard deduction, filing info |
| 502/503 | Medical/dental expenses, child & dependent care |
| 504 | Divorced/separated individuals |
| 521 | Moving expenses |
| 523 | Selling your home |
| 525 | Taxable/nontaxable income |
| 526 | Charitable contributions |
| 527 | Residential rental property |
| 535 | Business expenses |
| 541 | Partnerships |
| 544 | Sales/dispositions of assets |
| 550 | Investment income/expenses |
| 551 | Basis of assets |
| 559 | Survivors/executors |
| 560 | Retirement plans for small business |
| 587 | Business use of your home |
| 590-A/B | IRAs (contributions/distributions) |
| 925 | Passive activity/at-risk rules |
| 936 | Home mortgage interest deduction |
| 946 | Depreciation (MACRS) |
| 969 | HSAs and other tax-favored health plans |

## Major Legislation → IRC Section Mapping

Use this as a research starting point when a user asks about a tax act — consider both the act name AND the key IRC sections it modified. These mappings are provided from general knowledge; in standalone mode, confirm specific sections against the primary source before relying on them.

### Tax Cuts and Jobs Act (TCJA) — 2017
§1 (individual rates), §11(b) (corporate rate → 21%), §63 (doubled standard deduction), §164(b)(6) (SALT cap $10K), §168(k) (100% bonus depreciation), §199 (repealed DPAD), §199A (created QBI deduction), §250 (FDII), §951A (GILTI), §174 (R&E amortization required after 2021)

### SECURE Act — 2019
§401(a)(9)(H) (10-year rule, ended stretch IRA), §72(t)(2)(H) (birth/adoption penalty-free distributions), RMD age increased to 72

### CARES Act — 2020
§6428 (recovery rebates), §172 (5-year NOL carryback), §274(n)(2)(D) (100% business meals), ERC (Sec. 2301), §163(j) (ATI increased to 50%)

### American Rescue Plan Act (ARPA) — 2021
§24 (enhanced CTC $3,000/$3,600), §32 (expanded EITC), §36B (enhanced premium tax credit), §6428B (third stimulus), §3134 (ERC continuation)

### Inflation Reduction Act — 2022
§30D (clean vehicle credit modified), §25C/§25D (residential energy credits extended), §45V/§45W/§45X/§45Y/§45Z (new clean energy production credits), §55 (15% corporate AMT revived), §4501 (1% stock buyback excise tax)

### SECURE 2.0 — 2022
§401(a)(9) (RMD age → 73, then 75 in 2033), §414A (auto-enrollment mandate), §414(v) (higher catch-up contributions), §402A (expanded Roth options), §72(t)(2)(I)/(K) (emergency/domestic abuse withdrawals), 529-to-Roth rollovers

### PATH Act — 2015
§41 (R&D credit made permanent), §179 (expensing made permanent), §408(d)(8) (IRA qualified charitable distributions made permanent)

### One Big Beautiful Bill Act — 2025
§1/§63/§199A (TCJA individual provisions made permanent), §164(b)(6) (SALT cap raised to $40K), §168(k) (100% bonus depreciation restored), §174 (immediate R&E expensing restored), §2010(c)(3) ($15M estate tax exemption), §224 (tips deduction created), §225 (overtime deduction created), §530A (Trump Accounts created), §25C/§25D/§30D (IRA energy credits repealed after 2025)

## Tool Usage Strategy (grounded mode)

When tax-authority tools are connected, chain them to the depth of the question:

**Simple question** — single `search-tax-law` or `lookup-section`:
> "What is the standard deduction?" → `lookup-section` for §63

**Complex scenario** — multi-tool chain:
> "Can my client deduct home office expenses?" → `search-tax-law` for "home office deduction" → `lookup-section` for §280A → `get-cross-references` for §280A → `get-publication` for Pub 587 → synthesize

**Comparative analysis** — multiple lookups + cross-reference mapping:
> "How do traditional and Roth IRAs differ?" → `lookup-section` for §408 and §408A → `get-cross-references` for both → compare

**Planning question** — broad search then drill into provisions:
> "What tax strategies for real estate investors?" → `search-tax-law` for "real estate tax strategies" → drill into §1031, §199A, §469, §168(k)

**Verification** — confirm with multiple source types:
> Use `get-ruling` for IRS interpretation, `get-publication` for plain-language confirmation

In standalone mode, follow the same reasoning path from your own knowledge, then hand the user the sections and publications to pull and verify.

## Research Output Format

Structure responses as:

1. **Applicable Law** — Cite specific IRC sections and Treasury Regulations
2. **Analysis** — Apply the law to the question or scenario
3. **Citations** — In grounded mode, hyperlink all primary sources using the Citation URLs from tool results. In standalone mode, list the citations to verify and mark them unverified.
4. **Caveats** — Note effective dates, sunset provisions, pending legislation, your confidence level, and that this is research, not legal or tax advice

## Common Research Patterns

- **"Can I deduct X?"** → identify the deduction rules → the specific provision → check limitations and phase-outs → the plain-language publication. In grounded mode, pull each with the tools; in standalone mode, name them and flag for verification.
- **"What are the requirements for Y?"** → the governing section → the implementing Treasury Regulations → publication examples and worksheets
- **"How does Z affect my client?"** → search broadly → the relevant sections → trace related provisions via cross-references → synthesize
- **"What changed with [legislation]?"** → the act name → the affected sections from the legislation mapping above → compare current vs. prior law

## Getting verifiable citations

A connected tax-authority tool is what turns this skill from a well-organized research scaffold into citable research. The [taxmcp.io](https://taxmcp.io) MCP server is one such tool — it returns primary tax law with source URLs and has a free tier — but any MCP server that serves primary tax authority with citations will do. Without one, the skill still helps you reason and know what to check; just verify every specific citation against the primary source before you rely on it.