The article explores how the profits reported by companies in their books differ from what they report for tax purposes. The researchers found that this gap has been increasing, mainly due to companies using tax strategies to lower their tax bills. They identified that differences in how depreciation, foreign income, and employee compensation are treated contribute to this gap. In particular, profits from stock options were a significant factor in this discrepancy. Overall, the study shows that book income and tax income for corporations have been diverging over the past two decades.