Eligible ITC property is defined in former IRC § 48(a)(1) with reference to IRC § 38 (in fact, eligible property is often referred to as "section 38 property"). It included tangible personal property (other than heating or air conditioning units) and other tangible property (primarily machinery and equipment) that was closely integrated into the taxpayer's trade or business. Land, buildings, structural components contained in or attached to buildings, and other inherently permanent structures, generally were not eligible for ITC. Local law was not controlling with regard to property qualifying as tangible personal property for purposes of ITC.

Treas. Reg. § 1.48-1(c) provides examples of qualifying property, and states that

…'tangible personal property' means any tangible property except land and improvements thereto, such as buildings or other inherently permanent structures (including items which are structural components of such buildings or structures).

This same subsection states that "tangible personal property" includes

…all property (other than structural components) which is contained in or attached to a building. Thus, such property as production machinery, printing presses, transportation and office equipment, refrigerators, grocery counters, testing equipment, display racks and shelves, and neon and other signs, which is contained in or attached to a building constitutes tangible personal property for purposes of the credit allowed by section 38. Furthermore, all property that is in the nature of machinery (other than structural components of the building or other inherently permanent structure) shall be considered tangible personal property even though located outside a building. Thus, for example, a gasoline pump, hydraulic car lift, or automatic vending machine, although annexed to the ground, shall be considered tangible personal property.

In addition, the regulations provide examples of non-qualifying property. For example, "…buildings, swimming pools, paved parking areas, wharves and docks, bridges, and fences are not tangible personal property."

The Senate Report accompanying the enactment of the Revenue Act of 1978 provided additional insight into Congressional intent by providing further examples of qualifying and non-qualifying property.

…[T]he committee wishes to clarify present law by stating that tangible personal property already eligible for the investment tax credit includes special lighting (including lighting to illuminate the exterior of a building or store, but not lighting to illuminate parking areas), false balconies and other exterior ornamentation that have no more than an incidental relationship to the operation or maintenance of a building, and identity symbols that identify or relate to a particular retail establishment or restaurant such as special materials attached to the exterior or interior of a building or store and signs (other than billboards). Similarly, floor coverings which are not an integral part of the floor itself such as floor tile generally installed in a manner to be readily removed (that is it is not cemented, mudded, or otherwise permanently affixed to the building floor but, instead, has adhesives applied which are designed to ease its removal), carpeting, wall panel inserts such as those designed to contain condiments or to serve as a framing for picture of the products of a retail establishment, beverage bars, ornamental fixtures (such as coats-of-arms), artifacts (if depreciable), booths for seating, movable and removable partitions, and large and small pictures of scenery, persons, and the like which are attached to walls or suspended from the ceiling, are considered tangible personal property and not structural components. Consequently, under existing law, this property is already eligible for the ITC.