Now that companies such as General Electric, Microsoft, and Citigroup have accepted the premise that employee stock options are an expense, the debate on accounting for them is shifting from whether to report options on income statements to how to report them. The opponents of expensing, however, continue to fight a rearguard action, arguing that grant-date estimates of the cost of employee stock options, based on theoretical formulas, introduce too much measurement error. They want the reported cost deferred until it can be precisely determined—namely when the stock options are exercised or forfeited or when they expire.

A version of this article appeared in the December 2003 issue of Harvard Business Review.