This paper investigates the importance of deferred tax assets and liabilities for a sample of
large U.S. corporations between 1993 and 2004 and documents substantial heterogeneity in the
deferred tax positions of different firms. In 2004, 25 firms in a sample of 73 reported net deferred
tax assets and 48 reported net deferred tax liabilities. Firms differ substantially in the composition of
their deferred tax assets and liabilities. The largest components of deferred tax assets for sample
firms are Loss and Credit Carryforwards and Employment and Post-employment Benefits. The
largest components of deferred tax liabilities are Property, Plant & Equipment and Leases. Total
deferred tax assets for sample firms with net deferred tax assets in 2004 were $61.9 billion, while
total deferred tax liabilities for sample firms with net deferred tax liabilities were $223.8 billion. A
five percentage point decline in the federal statutory corporate tax rate could reduce net income at
sample firms with net deferred tax assets by as much as $8.8 billion, since a statutory rate cut would
reduce the value of deferred tax assets and this change would be reflected on the income statement.
We use data on the sales, market value, and assets of sample firms, relative to aggregate data for the
U.S. corporate sector, to estimate the aggregate value of deferred tax assets and liabilities.
firm’s total tax expense, an accounting concept, equals its statutory corporate tax rate times
its taxable book income. Taxable book income, which corresponds to income earned today that will
be taxed at some point in time, equals pre-tax book income less permanent differences between book
and tax income. Permanent differences arise when accounting rules and tax rules treat components
of income or expenses in different ways. Examples of permanent differences are the treatment of
municipal bond income, which is not included in taxable income but is included in book income, and
the reporting of fines and penalties, which are not are deductible for tax purposes but are deductible
in computing book earnings. Permanent book-tax differences do not generate deferred tax assets or
liabilities; their impact on the firm’s accounting earnings is fully reflected when they accrue.