Tax season is here, and someone built an MCP server for it. io.github.dma9527/irs-taxpayer provides 39 tools covering US individual tax calculations — and its defining feature is that none of them phone home.
The Server
The irs-taxpayer-mcp README describes it as:
"The most thorough open-source tax assistant for US individual taxpayers — powered by Model Context Protocol."
— irs-taxpayer-mcp README
The scope is broad: federal tax calculations with bracket breakdowns, AMT, NIIT (3.8%), and Additional Medicare Tax (0.9%). Standard vs. itemized deduction analysis with year-specific SALT caps ($10K for TY2024, $40K for TY2025 under the One Big Beautiful Bill Act). Over 20 tax credits including EITC with phase-in/plateau/phase-out curves, Child Tax Credit, AOTC, EV credits, and solar. Retirement strategies: Backdoor Roth, Mega Backdoor, Roth Conversion Ladder, optimal withdrawal order, RMD calculations. State taxes for all 50 states plus DC, with side-by-side comparison. Capital gains optimization with lot analysis, 0% bracket harvesting, and wash sale warnings. Quarterly estimates with safe harbor rules. Audit risk assessment.
The OBBB Act coverage is a notable detail — it includes the new deductions for tips ($25K), overtime ($12.5K), senior bonus ($6K for age 65+), and auto loan interest ($10K) that most tax software hasn't yet incorporated.
The Privacy Architecture
Every calculation runs locally. The privacy model from the README:
| Layer | Design |
|---|---|
| All tax calculations | 100% local execution — zero network calls |
| User data storage | Stateless — nothing saved between calls |
| Authentication | Zero credentials — no SSN, no IRS login |
| Remote data | Only public IRS info (form descriptions, deadlines) |
| Telemetry | None — no analytics, no tracking, no logging |
| Source code | Fully open-source (MIT) — audit every calculation |
This matters for tax data. People are understandably reluctant to send their income, deductions, and filing status to a cloud service. A stateless, offline tax calculator that an AI agent can invoke locally is a meaningfully different trust model than a web-based tax prep tool.
What to Know
Built by an anonymous developer (GitHub: dma9527). Created February 17, 2026 — nine days before this scan. TypeScript, MIT-licensed, published on npm. The README is available in four languages (English, Chinese, Spanish, Japanese). Zero stars, zero forks — very new. The standard disclaimer applies: this is not tax advice, and the accuracy of the calculations depends on the implementation correctly reflecting IRS rules. The source is open for audit, which is the right approach for a tool like this.
Score: 56. No flags.
Sources: dma9527 — GitHub · irs-taxpayer-mcp — repo · Scorecard: io.github.dma9527 (score 56)