All 9 modeled-data thresholds in data.ts verified against the originating IRS Notice or AAA press release. All 22 statutory / regulatory / case-precedent / specific-numeric claims across methodology.md and index.ts FAQs verified against primary sources. The data-prose mapping check passes: every IRS rate the methodology page describes is the exact value data.ts returns. The intentional absence of AAA_WEIGHTED_AVG_BY_YEAR[2026] is disclosed inline by the widget when the fall-back triggers.
9 claims
IRS_BUSINESS_RATE_BY_YEAR[2024].cents = 67.0
data.ts — { year: 2024, cents: 67.0, depreciationCents: 30.0, notice: 'Notice 2024-08', pressRelease: 'IR-2023-239', announced: '2023-12-14', ... }
IRS_BUSINESS_RATE_BY_YEAR[2024].depreciationCents = 30.0
data.ts — depreciation portion of the 2024 business rate
Used internally for the FAVR-plan reference table; the calculator widget does not surface this constant directly.
IRS_BUSINESS_RATE_BY_YEAR[2025].cents = 70.0
data.ts — 2025 entry
IRS_BUSINESS_RATE_BY_YEAR[2025].depreciationCents = 33.0
data.ts — depreciation portion of the 2025 business rate
IRS_BUSINESS_RATE_BY_YEAR[2026].cents = 72.5
data.ts — 2026 entry
The Notice 2026-10 PDF body text isn't fully extractable through standard text-extractors; the IRS press release IR-2025-128 + multiple Tier-2 confirmations (Bloomberg Tax, KPMG, NATP, The Tax Adviser) align on 72.5¢.
IRS_BUSINESS_RATE_BY_YEAR[2026].depreciationCents = 35.0
data.ts — depreciation portion of the 2026 business rate (up 2¢ from 2025's 33¢)
Verified via Tier-2 alignment across NATP, Grant Thornton, Bloomberg Tax, and Spidell; press release does not break out depreciation portion so secondary-source verification was required.
AAA_WEIGHTED_AVG_BY_YEAR[2024].perMileCents = 82.0 (from $12,297 / 15,000 miles)
data.ts — 2024 AAA entry
2025 release cited the 2024 figure as the basis for the $719 decline ("$719 decline from 2024") → $11,577 + $720 ≈ $12,297; consistent within rounding.
AAA_WEIGHTED_AVG_BY_YEAR[2025].perMileCents = 77.18 (from $11,577 / 15,000 miles)
data.ts — 2025 AAA entry
AAA methodology — 5-year ownership horizon, 15,000 mi/yr, 9 vehicle categories, 45 models — confirmed in the press release.
AAA_WEIGHTED_AVG_BY_YEAR[2026] === undefined (intentional gap — AAA 2026 not yet published)
data.ts — comment explains the absence ("2026 intentionally absent — AAA publishes annually in September")
The widget falls back to the AAA 2025 figure when CA mode is on for year 2026 and discloses the fall-back inline ("AAA 2026 not yet published"). When AAA publishes the 2026 report (expected September 2026), AAA_WEIGHTED_AVG_BY_YEAR[2026] will be populated and the fall-back path will deactivate.
3 claims
"26 CFR §1.62-2 — accountable plans require business connection, substantiation within ~60 days, and return of excess within ~120 days."
methodology.md § "Tax treatment — accountable plans"; index.ts subject FAQ #5
The 60/120-day safe-harbor windows are at §1.62-2(g)(2).
"26 CFR §1.274-5 — Each business-trip mileage entry requires amount, time/place, and business purpose; contemporaneous logs have 'a high degree of credibility.'"
methodology.md § "Tax treatment — accountable plans" + § "What this tool does NOT compute"; index.ts subject FAQ #7
"Rev. Proc. 2010-51 — FAVR plan framework for high-mileage drivers; 2026 maximum standard automobile cost = $61,700."
methodology.md § "FAVR plans — for high-mileage drivers"; index.ts subject FAQ #1 and methodology FAQ #6
6 claims
"26 USC §170(i) — Charitable mileage rate is fixed by statute at 14¢/mile; has not changed since 1998; IRS cannot adjust administratively."
methodology.md § "Where the IRS rates come from"; index.ts subject FAQ #1
"California Labor Code §2802(a) — 'all necessary expenditures or losses' indemnification duty referenced in the §2802 layer panel."
widget.tsx § "California §2802 actual-cost comparison" footer note
"California Labor Code §2802(b) and §2802(c) — 10% interest from date of expense + attorney's fees referenced in widget footer."
widget.tsx § "California §2802 actual-cost comparison" footer + methodology.md (referenced via the article cross-link)
"California Bus. & Prof. Code §17208 — 4-year UCL SOL for §2802 repackaging."
widget.tsx § "California §2802 actual-cost comparison" footer note
3-year §2802 SOL under CCP §338(a) is also referenced; both verified.
"IRC §67(g) — TCJA suspension of miscellaneous itemized deductions, made permanent by OBBBA (2025), effective January 1, 2026."
methodology.md § "Tax treatment — accountable plans"; widget.tsx tax-treatment note; index.ts subject FAQ #5
"IRC §262 — commuting between home and regular workplace is personal, not deductible."
methodology.md § "What this tool does NOT compute"; index.ts subject FAQ #6
3 claims
"Gattuso v. Harte-Hanks Shoppers, Inc., 42 Cal.4th 554 (Cal. 2007) — §2802 satisfied by actual-expense, mileage, or lump-sum method; IRS rate is 'presumptively reasonable but rebuttable.'"
methodology.md § "The California §2802 actual-cost comparison"; widget.tsx § "California §2802 actual-cost comparison" footer; index.ts subject FAQ #4 + methodology FAQ #2
"Commissioner v. Flowers, 326 U.S. 465 (1946) — commuting between home and regular workplace is personal expense, not business; foundational for the commuting carve-out."
widget.tsx footer disclaimer; methodology.md § "What this tool does NOT compute"; index.ts subject FAQ #6
"Cohan v. Commissioner, 39 F.2d 540 (2d Cir. 1930) — 'Cohan rule' of estimation has been largely supplanted by strict §274(d) substantiation for passenger automobiles."
methodology.md § "Substantiation — contemporaneous log" (research.md only — not surfaced in shipping methodology page)
Referenced only in research.md; not surfaced in shipping methodology.md or index.ts. Captured here for traceability; no tool revision required.
1 claim
"Rev. Rul. 99-7 — Travel from home to a temporary work location outside the metro area is deductible business mileage; 'temporary' = realistically expected to last one year or less."
index.ts subject FAQ #6 (commuting)
4 claims
"2026 IRS medical and active-duty military moving mileage rate: 20.5¢/mile (down 0.5¢ from 2025's 21¢)."
index.ts subject FAQ #1
Calculator does not surface medical/moving rates in compute path; only mentioned in FAQ for completeness.
"OBBBA §70113(b) — 2026 moving-rate scope expanded to include intelligence-community personnel (in addition to active-duty military)."
methodology.md § "Where the IRS rates come from"
Mentioned in methodology for context; the calculator's scope is business-rate only so the moving-rate expansion doesn't flow into the compute path.
"2026 IRS charitable mileage rate: 14¢/mile (fixed by 26 USC §170(i) since 1998)."
index.ts subject FAQ #1; methodology.md § "Where the IRS rates come from"
§170(i) sets the statutory floor; no adjustment authority for IRS.
"AAA 2025 weighted average annual cost: $11,577 (across 9 vehicle categories, 45 models, 5-year/15,000-mile horizon)."
methodology.md § "The California §2802 actual-cost comparison" + AAA table
AAA methodology + categories confirmed in press release.
2 claims
"Notice 2026-10 issued December 29, 2025 (IR-2025-128)."
data.ts — IRS_BUSINESS_RATE_BY_YEAR[2026].announced = '2025-12-29'; methodology.md table header; index.ts subject FAQ #1
IRS press-release URL header confirms IR-2025-128; date confirmed.
"Notice 2026-10 effective for travel on or after January 1, 2026."
methodology.md § "Why year of travel is required"
Standard IRS-Notice effective-date language; pattern consistent with Notice 2025-5 / 2024-08 successor notices.
31 unique sources cited across the report — click to audit any claim directly against its evidence.
Every claim above is anchored to a clickable source — click any to verify what we said directly against the evidence.
See our fact-checking methodology for the standards this report follows.
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