This study analyzed the effects of research and development (R&D) expenditures on corporate earnings to verify the asset characteristics of R&D spending. In particular, the contribution pattern and duration of R&D expenditures on future earnings were analyzed over multiple periods using Almon's distributed lag model. The analysis revealed that R&D expenditures had a significant positive effect on corporate earnings for 2 to 4 years into the future. The duration varied by industry: 4 years in the electronics and electrical industry and 3 years in the chemical industry. When distinguishing between ordinary and extraordinary R&D expenditures, ordinary R&D expenditures affected earnings for 1 to 2 years after spending, whereas extraordinary R&D expenditures showed a significant positive effect on earnings beginning 2 years after spending and lasting approximately 3 years. In light of the pattern of effects on earnings, depreciation of R&D expenditures appears to be appropriately handled using the declining balance method or the straight-line method over a 2 to 4 year period. The findings also suggest the need to more clearly define the criteria for distinguishing between development costs to be expensed (ordinary development costs) and development costs to be capitalized (development cost assets), as well as the need to restrict arbitrary accounting changes.