Maui cost segregation: CPA reference worksheet

For accountants, EAs, and tax preparers evaluating a Maui cost segregation study before signing off on the deduction. Engine methodology, state conformity, audit-defense documentation.

1. State conformity for Hawaii

Hawaii partially decouples from federal §168(k), HI requires addbacks for federal bonus depreciation with recovery on the regular MACRS schedule for state purposes. Combined with Hawaii's top 11% state rate, the state-side timing mismatch on cost-seg acceleration is meaningful. The federal §168(k) acceleration is unaffected; the HI-side reconciliation defers state benefit over the regular MACRS schedule.

Decoupling note: Hawaii has periodically modified bonus depreciation conformity. Verify current-year treatment with your CPA.

2. MACRS classification (Rev. Proc. 87-56 + IRS Pub. 946)

The engine assigns MACRS class lives by component category, derived from Rev. Proc. 87-56 asset class tables. Summary:

Component categoryRecovery periodIRS asset class (typical)
Personal property: FF&E, decorative finishes, certain electrical (kitchen plugs), carpet5-yearAsset class 57.0 (distributive trades) or building-specific
Personal property: office equipment, certain agricultural7-yearAsset class 00.11 (office furniture and equipment)
Land improvements: paving, landscaping, fencing, site lighting, hardscape15-yearAsset class 00.3 (land improvements)
Residential rental structure27.5-year SL§168(e)(2)(A)
Nonresidential real property (office, retail, industrial)39-year SL§168(e)(2)(B)

3. Bonus depreciation (current law)

OBBBA (One Big Beautiful Bill Act, signed July 2025) permanently restored 100% bonus depreciation under §168(k) for property placed in service in 2025 and later. Historical: 80% (2023), 60% (2024), 100% (2025 onward). Bonus applies to all assets with MACRS recovery periods of 20 years or less, so all 5, 7, and 15-year components reclassified by the study are bonus-eligible.

4. Engine methodology summary

For a Maui property, the Cost Seg Smart engine:

  1. Determines land allocation from county assessor records (if available and reliable) or from a statistical metro → state → national fallback. Premium land floor applies when reconciliation rf_raw exceeds 2.0.
  2. Applies RSMeans 2024 base $/SF costs to component categories, scaled by the geographic factor for Maui's metro tier.
  3. Applies BLS PPI to adjust RSMeans 2024 dollars to the property's acquisition-date dollars.
  4. Applies STR FF&E uplift if the property is a short-term rental (engine treats this differently from long-term rentals).
  5. Reconciles component-bottom-up sum against the depreciable basis to produce the final MACRS allocation.
  6. Runs 16-check QC validation (PASS / REVIEW / FAIL) with compound-OK downgrade logic before emitting the final study.

Full methodology at costsegsmart.com/methodology.

5. Audit defense documentation

Each Cost Seg Smart study includes written audit defense documentation as part of the deliverable. The package contains:

For complex audits requiring expert testimony, Cost Seg Smart engineering review is available on retainer.

6. CPA channel

Cost Seg Smart operates a CPA partner portal for white-label studies, branded client links, and partner margin tracking. If you're advising Maui-area clients regularly, email [email protected].