Deferred tax liability is a tax expense amount reported on a company's income statement that is not actually paid to the IRS in that time period, but is expected to be paid in the future. It arises because when a company actually pays less in taxes to the IRS than they show as an expense on their income statement in a reporting period.

Differences in depreciation expense between book reporting (GAAP) and IRS reporting can lead to differences in income between the two, which ultimately leads to differences in tax expense reported in the financial statements and taxes payable to the IRS.