For the purpose of avoiding undue refinement in accounting for additions to and retirements and replacements of service company property, all property will be considered as consisting of retirement units and minor items of property. Each company must maintain a written property units listing for use in accounting for additions and retirements of property and apply the listing consistently.

The addition and retirement of retirement units must be accounted for as follows:

When a retirement unit is added, the related cost must be added to the appropriate service company property account.

When a retirement unit is retired, with or without replacement, the related book cost must be credited to the property account in which it is included, determined in the manner provided in paragraph (d) of this section. If the retirement unit is of a depreciable class, the book cost of the unit retired and credited to service company property must be charged to the accumulated provision for depreciation applicable to the property. The cost of removal and the salvage must be charged or credited, as appropriate, to the depreciation account.

The addition and retirement of minor items of property must be accounted for as follows:

When a minor item of property that did not previously exist is added to service company property, the related cost must be accounted for in the same manner as for the addition of a retirement unit, as provided in paragraph (b)(1) of this section, if a substantial addition results, otherwise the charge must be to the appropriate maintenance expense account.

When a minor item of property is retired and not replaced, the related book cost must be credited to the property account in which it is included; and, in the event the minor item is a part of depreciable property, the account for accumulated provision for depreciation must be charged with the book cost and cost of removal and credited with the salvage. If, however, the book cost of the minor item retired and not replaced has been or will be accounted for by its inclusion in the retirement unit of which it is a part when the unit is retired, no separate credit to the property account is required when the minor item is retired.

When a minor item of depreciable property is replaced independently of the retirement unit of which it is a part, the cost of replacement must be charged to the maintenance account appropriate for the item. However, if the replacement effects a substantial betterment (the primary aim of which is to make the property affected more useful, more efficient, of greater durability, or of greater capacity), the excess cost of the replacement over the estimated cost at current prices of replacing without betterment must be charged to the appropriate property account.

The book cost of service company property retired must be the amount at which the property is included in the property accounts, including all components of construction costs. The book cost must be determined from the service company's records and, if this cannot be done, it must be estimated. Service companies must furnish the particulars of the estimates to the Commission, if requested. When it is impracticable to determine the book cost of each unit, due to the relatively large number or related small cost, an appropriate average book cost of the units, with due allowance for any differences in size and character, must be used as the book cost of the units retired.

The book cost of land retired must be credited to the appropriate land account. If the land is sold, the difference between the book cost (less any accumulated provision for related depreciation or amortization that has been authorized and provided) and the sale price of the land (less commissions and other expenses of making the sale) must be recorded in accounts 421.1, Gain on disposition of property (§ 367.4211) or 421.2, Loss on disposition of property (§ 367.4212), as appropriate.

The book cost less net salvage of depreciable service company property retired must be charged in its entirety to account 108, Accumulated provision for depreciation of service company property (§ 367.1080).

The accounting for the retirement of amounts included in account 303, Miscellaneous intangible property (§ 367.3030), and the items of limited-term interest in land included in the accounts for land and land rights, must be as provided for in the text of account 111, Accumulated provision for amortization of service company property (§ 367.1110), account 404, Amortization of limited-term property (§ 367.4040), and account 405, Amortization of other property (§ 367.4050).