What this site can do
- Pin every §179 / §168(k) figure to a primary IRS or Cornell LII source
- Look up manufacturer-published GVWR per trim for the canonical heavy-vehicle set
- Compute Year-1 §179 + bonus depreciation deterministically for any tax-year × vehicle × state combination
- Show the state-conformity overlay for the ~20 states that decouple from federal §168(k)
- Surface the hand-traced arithmetic walk-through so you can verify the math by hand
What this site cannot do
- Model your taxable income (§179 is subject to a business-income limitation under §179(b)(3) — the deduction can't exceed your business taxable income)
- Track prior-year §179 carryforwards or recapture from prior years
- Model listed-property rules (§280F(d)) — if business use drops below 50% mid-life, §179 + bonus dep are recaptured as ordinary income
- Account for trade-in basis treatment (post-TCJA, vehicle trade-ins recognize gain/loss immediately rather than rolling into the new vehicle's basis)
- Compare lease vs. buy (leased vehicles use the §280F lease inclusion table, not §179)
- Account for multi-state allocation, S-corp shareholder-level limitations, or partnership-level §179 elections
- Model the multi-year state recovery schedule for states with `decouple_partial` conformity (MN 80% over 5y, NC 85% over 5y, OH 5/6 over 6y) — calculator shows Year-1 state effect only
- Account for state-level alternative tax regimes (CA AMT, NY MTA surcharge, etc.)
- Distinguish between SUV-capped pickups and full-§179 pickups by cargo-bed length. Section 179(b)(5)(B)(ii) exempts pickups from the SUV cap when the cargo area is at least 6 ft AND not readily accessible from the passenger compartment. The decoder approximates this by exempting only pickups with GVWR ≥ 10,000 lb (i.e., heavy-duty trucks like F-250/F-350/Silverado 2500HD/Ram 2500/3500). Half-ton pickups (F-150, Silverado 1500, Ram 1500, Tundra) with regular-cab + 6.5–8 ft beds may also qualify for full §179 expensing, but the decoder treats them as SUV-capped to stay conservative. Confirm bed length and cargo-area accessibility with your CPA.
- Replace a CPA, EA, or tax attorney who knows your specific facts
If you take only one thing away
Run the calculator to get a useful first-order estimate, then verify with a credentialed CPA, EA, or tax attorney before placing a purchase order or claiming the deduction on a return. Tax law is fact-specific and updates frequently; the difference between a clean deduction and a recapture-triggering audit can turn on details (business-use percentage tracking, listed-property documentation, election timing on Form 4562) that no calculator can capture.
Source dates + freshness
Federal figures last verified 2026-05-12. See /sources for the full primary-source URL set with per-source last-verified dates. Manufacturer GVWR specs drift on model-year rollover (Aug-Oct); quarterly re-verification is on our run-book but always confirm current model-year GVWR with the dealer before purchase.