In some cases, an entity may grant awards with a graded vesting schedule (e.g., 25% of the award vests each year for four years), and, as a result, may separately estimate the fair value for each tranche (based on vesting date) of the award. As such, the deferred tax asset associated with each tranche of the awards will differ as they will have different grant date fair values. Because these awards will generally otherwise have the same grant date, exercise price, and expiration date, it may be difficult for the employer to determine, upon exercise, which tranche of the award was exercised and, in turn, which deferred tax asset should be deemed to have been recovered and/or whether there is an excess tax benefit or tax deficiency. If an entity is unable to determine which tranche of options was exercised, we believe it would be reasonable for the entity to assume that the first exercises were from the first tranche to vest and that subsequently exercised options were from any remaining options in the first tranche, followed by options in later tranches, in order of vesting (essentially a FIFO assumption).