โ ๏ธ Disclaimer: This tool provides estimates for educational and informational purposes only. It does not constitute tax, legal, or financial advice. Always consult a qualified tax professional.
Legal Notice: This software is provided "as is" without warranty of any kind. The authors and contributors are not tax professionals, CPAs, enrolled agents, or attorneys. No attorney-client, CPA-client, or fiduciary relationship is created by using this software. Tax laws change frequently and vary by jurisdiction. The calculations may contain errors, omissions, or may not reflect the most recent legislative changes. You are solely responsible for your tax filing decisions. The authors disclaim all liability for any damages arising from the use of this software. See DISCLAIMER.md for full legal notice.
Why This MCP?
Tax season is stressful. You're juggling W-2s, 1099s, deductions, credits, and trying to figure out if you should itemize or take the standard deduction. You Google "SALT deduction limit 2025" and get 10 conflicting articles.
This package provides a deterministic local tax engine with two interfaces. Direct local CLI commands can collect, validate, import, and calculate supported tax facts without invoking an MCP client or model. The MCP server lets an AI assistant call the same engine, but tax facts entered into a cloud-hosted MCP client may be processed by that client's model provider. No IRS login or SSN is required.
It includes OBBB provisions modeled for TY2025, federal brackets, selected credits and deductions, and explicitly supported state-tax paths. Unsupported state calculations fail closed instead of applying a rough top-rate estimate.
๐ Privacy Architecture
| Layer | Design |
|---|
| Deterministic engine | Local execution with no runtime network calls |
Direct intake, validate, and plan commands | No MCP connection, model invocation, telemetry, or automatic persistence |
| Local facts files | Strict versioned JSON, no identity fields, 1 MiB maximum, mode 0600 on POSIX |
| MCP server | Sends and stores no taxpayer data |
| MCP client and model | Privacy depends on the selected host and model provider; prompts and tool arguments may leave the machine |
| Authentication | No SSN, IRS login, or taxpayer identity required |
| Public IRS data | Bundled and versioned locally |
| Source code | Open-source MIT code with auditable calculations |
โก Getting Started
Option A: Direct local mode (recommended for taxpayer facts)
Install once, before entering any tax facts:
npm install --global irs-taxpayer-mcp
Run the guided local questionnaire. It does not start MCP or invoke a model:
irs-taxpayer-mcp intake --output taxpayer-facts.json
Or create and edit a strict local template:
irs-taxpayer-mcp template --output taxpayer-facts.json
irs-taxpayer-mcp validate --facts taxpayer-facts.json
Calculate directly through the deterministic engine:
irs-taxpayer-mcp plan --facts taxpayer-facts.json
irs-taxpayer-mcp plan --facts taxpayer-facts.json --json
New facts files are created with mode 0600 on POSIX. On Windows, the CLI rejects existing symbolic links but relies on the current user's filesystem permissions. Existing files are not replaced unless --force is explicit. Imported JSON is limited to 1 MiB, rejects symbolic links and unknown fields, and does not accept names, SSNs, addresses, employer IDs, or account numbers.
Using npx may download the public package before execution, but the direct commands do not send the facts file or its values over the network.
Option B: MCP mode for AI assistants
The MCP server makes no network requests and stores no taxpayer data. However, facts typed into an MCP client may be processed by that client's model provider. Use direct local mode or a local-model MCP client when end-to-end local handling is required.
MCP Step 1: Add to your AI assistant
Add this to your MCP client configuration:
Claude Desktop (~/Library/Application Support/Claude/claude_desktop_config.json):
{
"mcpServers": {
"irs-taxpayer": {
"command": "npx",
"args": ["-y", "irs-taxpayer-mcp"]
}
}
}
Kiro (.kiro/settings/mcp.json):
{
"mcpServers": {
"irs-taxpayer": {
"command": "npx",
"args": ["-y", "irs-taxpayer-mcp"]
}
}
}
Cursor: same format in Cursor's MCP settings.
MCP Step 2: Restart your AI assistant
After saving the config, restart the app. The MCP server will auto-download and connect.
MCP Step 3: Ask supported tax questions
The client model converts natural language into tool arguments. Do not enter real taxpayer facts here unless the selected MCP host and model satisfy your privacy requirements:
- "Calculate my federal tax: $150k income, married filing jointly, 2 kids"
- "Compare California vs Texas vs Washington for $200k income"
- "I'm a freelancer making $80k: what are my quarterly estimated taxes?"
- "What tax credits am I eligible for? AGI $60k, single, one child"
- "Should I itemize or take the standard deduction? I pay $15k in mortgage interest and $12k in state taxes"
- "Explain the Backdoor Roth IRA strategy"
- "How much is the EITC for a family of 4 earning $35k?"
- "I exercised ISOs this year: will I owe AMT?"
- "Help me plan my year-end tax moves. I have a 401k and HSA."
Alternative: Docker
docker build -t irs-taxpayer-mcp .
docker run -i irs-taxpayer-mcp
Alternative: Streamable HTTP Transport
npx irs-taxpayer-mcp --http --port 3000
HTTP mode is stateless and binds only to a loopback host by default. Browser requests must use an exact allowed Origin. Add a trusted browser Origin with a repeatable flag:
npx irs-taxpayer-mcp --http \
--allowed-origin https://trusted-client.example
The legacy --sse flag remains a deprecated alias for --http. The old /sse and /messages endpoints are not exposed.
All tools use the current MCP registerTool API. Each advertises read-only annotations and an output schema, and returns both human-readable text and structuredContent. Error results include a stable error code, message, and recovery suggestion.
The 1.0 flagship generate_tax_plan workflow returns domain structured results, assumptions, official source provenance, a calculation trace, and explicit unsupported boundaries. The deterministic engine performs no network requests, persistence, or telemetry. Its structured privacy metadata reports whether the MCP adapter or direct CLI path was used. Unsupported tax years, state profiles, and required worksheet facts fail closed. See Local Tax Planner 1.0 Contract.
Federal Tax Calculations
| Tool | What it does |
|---|
calculate_federal_tax | Full federal tax with bracket breakdown, AMT, NIIT (3.8%), Additional Medicare Tax (0.9%), QBI deduction, SE tax, capital gains, CTC |
get_tax_brackets | Tax brackets and standard deduction by filing status and year |
compare_filing_statuses | Side-by-side comparison of all 4 filing statuses for the same income |
estimate_quarterly_tax | Estimated quarterly payments (1040-ES) with safe harbor guidance |
calculate_total_tax | Combined federal + state tax in one call, with take-home pay and monthly income |
calculate_w4_withholding | Per-paycheck withholding estimate with step-by-step W-4 form recommendations |
Deduction Analysis
| Tool | What it does |
|---|
list_deductions | Browse all deductions with eligibility rules, limits, and forms |
standard_vs_itemized | Compare standard vs itemized with year-specific SALT cap ($10K for TY2024, $40K for TY2025) |
Tax Credits
| Tool | What it does |
|---|
list_tax_credits | 20+ federal credits: CTC, EITC, AOTC, EV, solar, saver's credit, and more |
check_credit_eligibility | Quick screening based on your income, family, and situation |
calculate_eitc | Precise EITC calculation with phase-in/plateau/phase-out for 0-3 children |
Retirement & Strategy
| Tool | What it does |
|---|
get_retirement_accounts | IRA, Roth, 401k, SEP, Solo 401k, HSA, 529: limits, tax treatment, tips |
get_retirement_strategy | Backdoor Roth, Mega Backdoor, Roth Conversion Ladder, Tax Loss/Gain Harvesting |
Tax Planning & Scenarios
| Tool | What it does |
|---|
generate_tax_plan | Privacy-first local plan with structured results, assumptions, sources, trace, and explicit boundaries |
get_tax_planning_tips | Personalized year-end optimization: 401k maxing, HSA, Roth conversion, tax-loss harvesting, charitable bunching |
compare_tax_years | Compare TY2024 vs TY2025 to see how bracket changes and OBBB affect your tax |
estimate_self_employment_tax | Full SE tax breakdown: Schedule C profit, SE tax, QBI deduction, quarterly payments, SEP/Solo 401k limits |
analyze_mortgage_tax_benefit | Mortgage interest + property tax deduction analysis with year-specific SALT cap |
analyze_education_tax_benefits | AOTC vs Lifetime Learning Credit comparison, student loan deduction, 529 plan guidance |
State Taxes
| Tool | What it does |
|---|
get_state_tax_info | Reference data and notes for all 50 states + DC |
estimate_state_tax | Estimate supported state paths; unsupported bracket data fails closed |
compare_state_taxes | Compare states only when every requested calculation is supported |
list_no_income_tax_states | All 9 states with no broad individual income tax |
| Tool | What it does |
|---|
get_tax_deadlines | Key IRS dates and deadlines by tax year |
check_refund_status | How to check your refund (guidance only: no IRS account access) |
get_irs_form_info | Info about 14 common IRS forms (1040, W-2, 1099s, Schedules, etc.) |
| Tool | What it does |
|---|
calculate_obbb_deductions | Calculate all 4 new OBBB deductions: tips, overtime, senior bonus, auto loan interest |
what_changed_between_tax_years | Diff any two supported years: brackets, deductions, credits, SALT, and OBBB provisions |
Full Reports & Analysis
| Tool | What it does |
|---|
generate_full_tax_report | Estimation report: income, deductions, federal, FICA, supported state tax, take-home, and refund inputs |
process_1099_income | Process multiple 1099 forms (NEC, INT, DIV, B, MISC) with tax impact by category |
get_personalized_tax_calendar | Personalized deadlines based on your situation (self-employed, extension, investments) |
analyze_paycheck | Verify paycheck withholding accuracy, project annual tax, suggest W-4 adjustments |
compare_mfj_vs_mfs | MFJ vs MFS comparison with tax diff and all MFS restriction warnings |
simulate_tax_scenario | What-if modeling: income changes, relocation, Roth conversion, 401k, filing status |
assess_audit_risk | IRS audit risk scoring with red flag identification and mitigation tips |
get_tax_document_checklist | Personalized filing document checklist based on your income and life events |
optimize_capital_gains | Investment lot analysis: 0% bracket harvesting, tax-loss harvesting, wash sale warnings |
plan_retirement_withdrawals | Optimal withdrawal order (Traditional/Roth/Taxable), RMD calculation, Roth conversion |
plan_multi_year_taxes | 3-5 year tax projection with bracket management and age milestones |
analyze_relocation_taxes | In-depth state relocation analysis with multi-year savings and SALT impact |
Guidance & Feedback
| Tool | What it does |
|---|
run_tax_health_check | Report tool coverage and the freshness of built-in tax-year data |
lookup_tax_rule | Search the built-in tax knowledge base |
get_form_filing_guide | Provide step-by-step guidance for supported IRS forms |
submit_feedback | Generate a prefilled GitHub issue link without transmitting tax data |
๐ Tax Year Coverage
TY2024
Supported historical calculation year using IRS Revenue Procedure 2023-34. Standard deduction $14,600 (single) / $29,200 (MFJ). CTC $2,000. SALT cap $10,000.
TY2025
Reflects OBBB signed July 4, 2025:
- Standard deduction: $15,750 (single) / $31,500 (MFJ) / $23,625 (HoH)
- Child Tax Credit: $2,200 per child (up from $2,000)
- SALT cap: $40,000 for AGI โค $500K (was $10,000)
- New deductions: tips ($25K), overtime ($12.5K), senior bonus ($6K age 65+), auto loan interest ($10K)
- 401k catch-up: $11,250 for ages 60-63 (SECURE 2.0)
TY2026
Uses IRS Revenue Procedure 2025-32 and the SSA 2026 contribution and benefit base:
- Standard deduction: $16,100 (single) / $32,200 (MFJ) / $24,150 (HoH)
- Child Tax Credit: $2,200 per qualifying child, with up to $1,700 refundable
- SALT cap: $40,400 for MAGI up to $505,000; $20,200 and $252,500 for MFS
- Social Security wage base: $184,500
- Updated ordinary, capital-gains, EITC, and AMT thresholds
Supported Scope and Boundaries
This project is a deterministic estimation and planning engine, not tax preparation or filing software.
- Federal estimates cover the modeled TY2024 through TY2026 inputs exposed by each tool. They do not implement every Form 1040 line, schedule, election, limitation, carryforward, or dependency rule.
- State reference information covers all 50 states and DC. Numeric estimates require an exact tax-year profile: TY2024 supports AK, CA, FL, NV, SD, TN, TX, and WY; TY2025 and TY2026 support AK, FL, NH, NV, SD, TN, TX, and WY. California TY2024 supports single and married brackets. Other state-year and filing-status paths return an error.
- State calculations do not yet model part-year or nonresident allocation, every local tax, or separate HoH and MFS brackets.
- QBI, AMT, audit-risk, retirement, relocation, and multi-year outputs are planning estimates with documented simplifications.
- Refund projections depend only on the inputs and refundable credits modeled by the selected tool. They are not an IRS refund determination.
- The server does not generate a tax return, sign a return, transmit MeF data, or provide filing eligibility validation.
See ROADMAP.md for the remaining work toward a filing-grade federal return engine.
๐งฎ Calculation Engine
| Feature | Status |
|---|
| Federal income tax (7 brackets ร 4 statuses) | โ
|
| Long-term capital gains (0%/15%/20%) | โ
|
| Capital-loss netting, annual limit, carryovers | Planning-grade |
| Social Security benefit taxation | Publication 915 planning model |
| Retirement distributions and early tax | Planning-grade from supplied 1099-R facts |
| Self-employment tax (SS + Medicare) | โ
|
| Net Investment Income Tax (3.8% NIIT) | โ
|
| Additional Medicare Tax (0.9%) | โ
|
| Alternative Minimum Tax (AMT) | Modeled with preferential rates and stated preference-item limits |
| QBI Deduction (Section 199A) | Planning-grade with wage, UBIA, and SSTB limits |
| Child Tax Credit with phase-out | โ
|
| AOTC and Lifetime Learning Credit | Form 8863 planning model |
| EITC TY2024/TY2025/TY2026 calculation | โ
|
| Standard vs itemized deduction | โ
|
| Year-specific SALT cap (OBBB) | โ
|
| State reference data (50 states + DC) | โ
|
| State numeric estimates | Supported paths only |
| 20+ federal credit reference and screening | โ
|
| Retirement account reference and planning | Planning estimate |
| W-4 withholding calculator | Planning estimate |
Numeric regression tests cite IRS Revenue Procedures, IRC sections, and relevant legislation. Reference and planning tools may summarize rules that are not fully represented in the calculation engine.
๐๏ธ Build from Source
Requires Node.js 20 or later.
git clone https://github.com/dma9527/irs-taxpayer-mcp.git
cd irs-taxpayer-mcp
npm install
npm run build
npm start
npm run dev
๐ Found a Bug?
๐ค Contributing
Contributions welcome. Please ensure:
- All tests pass (
npm test)
- Build succeeds (
npm run build)
- No
any types in TypeScript
- Data changes include IRS source citations
See CONTRIBUTING.md for full guidelines.
๐ License
MIT
