Effective Tax Rate vs Cash Tax Rate

Pull up any company's income statement and you'll find a tax expense line, usually working out to something close to the statutory rate. Pull up the cash tax note buried in the footnotes and the actual check written to the IRS can look nothing like it. Neither number is wrong — they're answering different questions.

The effective tax rate is tax expense divided by pretax income, as reported under GAAP or IFRS. It includes a current portion (taxes owed this year) and a deferred portion (taxes that will be owed or saved in a future year because book income and taxable income diverge). The cash tax rate is what was actually paid this year, found in the cash flow statement or the income tax footnote. The gap between the two is the deferred tax provision — a timing difference, not a permanent one.

Why the two diverge

The most common driver is depreciation. Tax law in most jurisdictions lets companies depreciate assets faster than GAAP book depreciation (accelerated methods, bonus depreciation), which shrinks taxable income today relative to book income. The company books a normal-looking tax expense on the income statement but pays less cash tax now — the difference accrues as a deferred tax liability, to reverse (and reduce future cash tax) once book depreciation catches up. Net operating loss carryforwards, stock-compensation deductions, and revenue-recognition timing differences work the same way: they widen the gap without changing the total tax bill over the asset's life.

Worked example

A company reports pretax income of $500m and a book tax expense of $120m, an effective rate of 24%. Its cash tax note shows only $60m of cash taxes actually paid, a cash rate of 12%. The $60m difference is added to the deferred tax liability on the balance sheet, driven mostly by accelerated depreciation on a recent capex program. It is not a permanent saving: as those assets age, book depreciation will exceed tax depreciation, taxable income will run ahead of book income, and the cash tax rate will rise above the book rate to pay the deferral back.

What this means in practice

For valuation, cash taxes are what matter — a DCF should use the cash tax rate (or a normalized long-run rate), not the book effective rate, because free cash flow is a cash concept. For earnings quality, a persistently and sharply falling cash tax rate driven by continuous heavy capex or serial acquisitions is sustainable as long as investment continues; if investment slows, the deferred liability starts reversing and cash taxes catch up, squeezing free cash flow just when the market isn't expecting it.