This paper presents a new approach to estimating the longrun internal rate of return (IRR) for the firm from the accountant's rate of profit based on published financial statements. The model developed for estimating the IRR includes both capital and net working asset investments. Modelling and estimating the growth of the firm is an integral part of the approach. Furthermore, estimating the parameters describing the long‐run financing behavior of the firm is presented based on discounted average funds flow statements. Finally, the approach is applied on the financial data of a large Finnish business enterpris