Section 174 & 174A · Brief · Working level
Pilot models and prototypes: Section 174's reach versus Section 41 supplies
A pilot model under the Section 174 regulations is any representation or model produced to evaluate and resolve uncertainty — including a full-scale, functional, even saleable unit. The 174 definition sweeps broader than the Section 41 supplies rules, and the two computations diverge on the same prototype.
The Section 174 pilot-model rule is broader than most practitioners' instincts. Under Treas. Reg. §1.174-2(a)(4), a "pilot model" is any representation or model of a product — including a fully functional, full-scale one — produced to evaluate and resolve uncertainty concerning the development or improvement of the product. The costs of producing it are research or experimental expenditures: currently deductible if domestic under Section 174A, capitalized over 15 years if the work is performed abroad. The full text sits in Title 26 of the eCFR.
How far the 174 regulations reach
The regulations, overhauled in 2014 to settle decades of skirmishing, resolve three recurring disputes in the taxpayer's favor:
- Full-scale and functional counts. A working aircraft, a drivable vehicle, a deployable machine — the first article built to prove out the design is a pilot model. "Model" does not mean miniature.
- Later sale does not disqualify. Eligibility is tested when costs are incurred. If uncertainty existed then, a subsequent sale of the unit (or its use in the business) does not strip Section 174 character from the development costs. The regulations' "depreciable property" exclusion is applied narrowly: it excludes costs of acquiring or producing property of the type the research has already de-risked, not the research articles themselves.
- Component-level uncertainty suffices. Uncertainty about the appropriate design of a component can qualify the costs attributable to that component even where the overall product design is settled.
The line that survives: once uncertainty is resolved and the taxpayer begins producing units on the established design, subsequent production costs are inventory or depreciable-asset costs, not R&E. The first ten units built while the design still moves can qualify; unit two hundred off a frozen design does not. The transition point is a fact question examiners probe with engineering change orders and design-freeze documentation.
The Section 41 supplies contrast
The research credit sees the same prototype through a narrower aperture. Section 41 QREs include supplies — tangible property other than land or depreciable property — used in the conduct of qualified research, plus qualifying wages and 65% of contract research. Three divergences matter:
| Dimension | Section 174 pilot model | Section 41 supplies |
|---|---|---|
| Overhead and indirect costs | Included (allocable share) | Excluded |
| Depreciation on equipment used | Included as SRE cost | Excluded (not a supply) |
| Qualification test | Uncertainty at time costs incurred | Four-part test, business-component level, shrink-back rule |
So the 174 number for a prototype is typically larger than the credit number built on the same facts — one reason copying a credit study into the SRE pool understates it, a theme that runs through the broader cost-allocation rules. Extraordinary-utility supplies and prototypes later held for sale draw additional credit-side scrutiny that has no 174 analogue.
Under restored domestic expensing the stakes are mostly timing-neutral federally, but the classification still controls foreign builds, 60-month election pools, and open 2022–2024 years — the same places every 174 boundary question now lives (see the transition rules). And where prototype work is performed under contract for a customer, whose expenditure it is comes first: see who capitalizes contract development.
Frequently asked questions
- What is a pilot model under Section 174?
- Treas. Reg. §1.174-2(a)(4) defines a pilot model as any representation or model of a product produced to evaluate and resolve uncertainty about the product during its development or improvement. It includes a fully functional, full-scale unit — there is no requirement that it be a mock-up, and costs of producing it qualify as R&E expenditures.
- Can the cost of a prototype the company later sells still be a Section 174 expenditure?
- Yes. Under the pilot-model regulations, eligibility is determined when costs are incurred, based on whether uncertainty exists at that time. A later sale of the unit does not retroactively disqualify the development costs, though under Section 41 a supply that becomes property held for sale raises separate issues for the credit.
- Are prototype costs treated the same under Section 174 and the Section 41 credit?
- No. Section 174 captures the full cost of producing a pilot model, including allocable overhead and depreciation. Section 41 counts only supplies (non-depreciable tangible property) and qualified wages, excludes overhead entirely, and applies the four-part test at the business-component level. The same prototype routinely produces different numbers in the two computations.