The fact that incumbent firms can immediately deduct research and development (R&D) investments from taxable income is generally believed to give them a strategic advantage over new firms that cannot deduct the investment cost, but instead generate a net operating tax loss carryover. Using an analytical model, we show that this conventional wisdom need not hold in a competitive environment. We examine operating and investment decisions in a duopolistic industry in which an initial investment in R&D yields an immediate tax benefit for one firm, but creates a net operating loss carryover for the other firm. If both firms invest in R&D, the firm with the net operating loss carryover makes more aggressive capital investment decisions following successful R&D. This may deter the incumbent firm from investing in R&D despite the lower after‐tax costs of this investment. Changing the tax loss carryover rules would thus not only affects start‐up or loss firms, but would also affect the investment decisions of profitable firms in the same industry.