Profit measurements have major corporate and social consequences. Calculations of profit already earned (ex post income) or that anticipated (ex ante income) influence corporate tax liabilities, dividend levels, incentive scheme payments, regulatory intervention, management goals, expansion or closure decisions, outsourcing criteria, acceptance or rejection of investment proposals, and other key business and political policies and actions. This entry describes key assumptions about time that underlie widely held and promoted views of profit calculation. It identifies flaws in those assumptions, and overviews the literature that addresses those weaknesses.