Русско-англо-русский юридический словарь

Repair and maintenance cost is expensed unless the useful life of the asset is materially lengthened or the productivity of the asset is materially increased. (Fundamentals of Oil & Gas Accounting by Charlotte J. Wright, ‎Rebecca A. Gallun)

You should defer expenses when generally accepted accounting principles or international financial reporting standards require that they be included in the cost of a long-term asset, and then charged to expense over a long period of time. For example, you may have to include the cost of interest in the cost of a constructed asset, such as a building, and then charge the cost of the building to expense over the useful life of the entire asset in the form of depreciation. In this case, the cost of the interest is a deferred expense. (accountingtools.com)