Live verification
Every number, re-verified.
The Arc & Ledger Tax Reference MCP server is audited by an automated harness that checks its live output against IRS and FinCEN primary sources. The full audit runs at every release; a 24-check monitor re-runs against production every day. This page is generated from the actual results - no hand-picked screenshots.
Verification layers
| Layer | Scope | Cadence | Last run | Result |
|---|---|---|---|---|
| Repository test suite | vitest - protocol, golden outputs, governance, widgets | Release gate | 2026-07-30 | 212 / 212 PASS |
| Accuracy audit | 48 assertions on live output vs IRS / FinCEN primary sources | Release gate | 2026-07-30 | 48 / 48 PASS |
| Protocol audit | 23 checks - handshake, error handling, CORS, both editions | Release gate | 2026-07-30 | 23 / 23 PASS |
| Accessibility | WCAG AA contrast, light + dark themes | Release gate | 2026-07-30 | 12 / 12 PASS |
| Press-kit claims audit | 62 checks - no unverified stats, no blanket competitor claims | Release gate | 2026-07-30 | 62 / 62 PASS |
| Continuous live monitor | 24 production checks - accuracy, protocol, governance | Daily (automated) | 2026-07-31 | 24 / 24 PASS |
Release-gate layers ran against build v0.15.1 on July 30, 2026 (212 + 48 + 23 = 283 functional and protocol checks; zero server defects found). The daily monitor re-verifies the production endpoint you are using right now.
Audited examples - real calls, checked math
Penalty coordination
estimate_irs_penalty - $10,000 owed, 3 months late, not filed
$1,350 failure-to-file + $150 failure-to-pay + ≈$175 interest
Generic calculators report $1,500 FTF; the correct §6651(c)(1) coordination is $1,350 + $150.
2026 mid-year mileage change
estimate_accountable_plan - 1,000 business miles, on/after July 1, 2026
$760 at 76.0¢/mile; first-half miles correctly return 72.5¢
The IRS changed the rate mid-year (Announcement 2026-11). Annual-cycle software updates late; the server was correct on day one.
Sixty-day penalty floor
estimate_irs_penalty - $500 owed, 3 months late, not filed
Failure-to-file equals the full $500 balance (floor does not exceed the tax)
The $525 minimum is correctly capped at the tax due - an edge case most penalty pages get wrong.
Rules verified against primary sources
- IRC §6651(c)(1) failure-to-file / failure-to-pay coordination (4.5% net) and the $525 sixty-day floor
- 2026 split-year mileage: 72.5¢/mi first half, 76.0¢/mi on or after July 1 (Notice 2026-10, Announcement 2026-11)
- IRC §6654 quarterly safe harbors (90% current-year, 100%/110% prior-year)
- FBAR $10,000 aggregate threshold and FinCEN filing deadlines; Form 8938 thresholds
- Form 5472 for foreign-owned single-member LLCs, including the $25,000 penalty screen
- US–Turkey treaty withholding rates (dividends, interest, royalties)
- §280A(g) Augusta rule 14-day exclusion
- 27.5-year residential rental depreciation
- Nonresident filing deadlines (April 15 with US wages, June 15 without) and extension dates
Latest daily monitor run - every check
| Check | Detail | Result |
|---|---|---|
| handshake.initialize | arc-ledger-mcp | PASS |
| handshake.protocol_version | 2025-06-18 | PASS |
| catalog.13_tools | 13 tools | PASS |
| catalog.schemas_and_hints | inputSchema + readOnlyHint on every tool | PASS |
| accuracy.penalty_ftf_coordination | 4.5% net x 3 months FTF + 0.5% x 3 FTP | PASS |
| accuracy.penalty_cites_irs | PASS | |
| accuracy.penalty_525_floor | 60-day minimum floor: FTF equals full $500 balance, not $67.50 | PASS |
| accuracy.mileage_76_cents | on/after 2026-07-01 | PASS |
| accuracy.mileage_72_5_cents | first half 2026 | PASS |
| accuracy.fbar_required | $25k aggregate exceeds $10k threshold | PASS |
| accuracy.5472_penalty_25000 | PASS | |
| accuracy.treaty_turkey_dividends | PASS | |
| accuracy.augusta_14_day | 14 days x $500 excluded | PASS |
| accuracy.rental_27_5yr | ($300k x 80%) / 27.5 = $8,727 | PASS |
| accuracy.quarterly_safe_harbor | PASS | |
| accuracy.deadlines_2026 | PASS | |
| accuracy.cp2000_decoded | PASS | |
| governance.disclaimer_present | PASS | |
| governance.no_promo_links | PASS | |
| protocol.unknown_tool_error | Unknown tool | PASS |
| protocol.bad_args_rejected | PASS | |
| protocol.unknown_method_error | PASS | |
| protocol.get_version | GET /version -> 200 | PASS |
| protocol.cors_preflight | OPTIONS -> 204 | PASS |
Generated July 31, 2026 at 3:51 AM UTC against https://mcp.arcandledger.com/directory/mcp. Listed on the official MCP Registry as com.arcandledger/tax-tools (active since 2026-07-28).
What this page does not claim
- It does not prove correctness for every possible input - it proves the audited cases pass, in public, on a schedule.
- It does not compare against named competitors; coverage differs by product.
- The tools provide general information, not tax advice; no practitioner-client relationship is created.
Found a number you believe is wrong? That is exactly what support is for - every report is reviewed against the cited primary source. See also the directory documentation, server overview, and privacy policy.