CFA Level I Exam · Analysis of Income Taxes

Tax Rate Changes and Effective Tax Rate Reconciliation

Updated 7 October 2026

When the enacted tax rate changes, you remeasure deferred tax assets and liabilities at the new rate, and the adjustment goes through income tax expense. The effective tax rate is income tax expense ÷ pretax income. A reconciliation explains the gap between statutory and effective rates item by item.

Understand Tax Rate Changes and Effective Tax Rate Reconciliation

A deferred tax balance is a temporary difference multiplied by a tax rate. It is meant to show the tax you will pay or save when the difference reverses. So if the rate that will apply on reversal changes, the balance must change too.

Under IFRS and US GAAP, you measure deferred taxes using the enacted (or substantively enacted) rate expected to apply when the difference reverses. When a new rate is enacted, you remeasure all existing deferred tax balances. The change is normally recognised in income tax expense in the period of enactment, not in the period the rate takes effect.

The direction matters. A rate cut shrinks a deferred tax liability (DTL), which lowers tax expense and raises net income. A rate cut also shrinks a deferred tax asset (DTA), which raises tax expense and lowers net income. A rate increase does the reverse. A company with a net DTL gains from a cut. A company with a net DTA loses.

The statutory rate is the tax rate set by law in the home jurisdiction. The effective tax rate is income tax expense ÷ pretax income, using the income statement figures. The two rarely match. Reasons include foreign income taxed at other rates, tax-exempt income, non-deductible expenses, tax credits, changes in valuation allowance, and rate-change remeasurement.

A reconciliation in the notes starts at the statutory rate and lists each item that moves you to the effective rate. Analysts use it to judge whether the effective rate is sustainable. One-off items, such as a remeasurement gain, should not be extrapolated into forecasts. Also note that the effective rate uses tax expense, not cash taxes paid. Cash taxes paid can differ because of deferred taxes.

Key formulas to remember

Effective tax rate: Effective tax rate = Income tax expense ÷ Pretax income; Use income tax expense (current + deferred), not cash taxes paid.
Deferred tax balance: DTL or DTA = Temporary difference × Enacted tax rate expected on reversal; Or equivalently, the tax base gap times the rate.
Effect of a rate change on a deferred tax balance: Change = Balance × (New rate ÷ Old rate − 1); A cut shrinks both DTLs and DTAs. Remeasure at enactment.
Income tax expense: Income tax expense = Taxes payable (current tax) + Change in DTL − Change in DTA; Remeasurement from a rate change sits inside the deferred portion.
Statutory-to-effective reconciliation: Effective rate = Statutory rate ± each reconciling item (as % of pretax income); Items include foreign rate differences, tax-exempt income, credits, non-deductible costs, valuation allowance changes.

How to solve Tax Rate Changes and Effective Tax Rate Reconciliation questions

Use this order for any question on rate changes or reconciliations. It keeps signs and directions straight.

1Identify what is asked: a remeasurement amount, an effective rate, or an interpretation of reconciling items.
2For a rate change, separate DTLs from DTAs. Remeasure each at the new enacted rate.
3Compute each change as balance × (new rate ÷ old rate − 1), or recompute as temporary difference × new rate.
4Decide the effect on tax expense. A DTL decrease lowers expense. A DTA decrease raises expense. Increases do the opposite.
5For the effective rate, divide income tax expense by pretax income. Do not use cash taxes paid.
6For a reconciliation, first check how each item is shown. If it is already a tax amount, divide it by pretax income only. If it is a pretax amount, such as exempt income, multiply it by the statutory rate to get its tax effect, then divide by pretax income. If it is already a percentage, use it as it is.
7Add or subtract each item from the statutory rate, with favourable items reducing the effective rate.
8Judge sustainability. Treat one-off items such as remeasurement as non-recurring when forecasting.

Quickest way: Direction-first shortcut

When to use it: Use this when the options are far apart or when the question only asks about direction of the effect on income, expense or the effective rate.

Ask: is the net balance a DTL or a DTA?
Rate cut with DTL means lower tax expense and higher net income. Rate cut with DTA means higher tax expense and lower net income.
A rate rise reverses both results.
Scale quickly: the change equals balance × percentage change in the rate.
Eliminate options with the wrong sign first, then check the size.

Common mistakes in Tax Rate Changes and Effective Tax Rate Reconciliation

Treating a rate cut as always good for earnings.
Lower rate sounds like lower tax, so students ignore the DTA side.
Fix: Check whether the company holds a net DTL or net DTA. Only a net DTL gains from a cut.
Remeasuring when the new rate takes effect instead of when it is enacted.
Students link the change to the first year of the new rate.
Fix: Recognise the effect in the period of enactment of the law.
Using cash taxes paid to compute the effective tax rate.
Cash taxes are easier to find in the cash flow statement.
Fix: Use income tax expense from the income statement divided by pretax income.
Applying the old rate to the new temporary difference.
Students forget the balance was built at the old rate.
Fix: Either scale the existing balance by new ÷ old rate, or recompute the difference × new rate.
Forecasting the current effective rate forever.
The reported rate looks like a clean number.
Fix: Read the reconciliation. Strip out one-offs such as remeasurement, valuation allowance changes and credits that will not recur.
Getting the sign wrong on reconciling items.
Tax-exempt income and credits lower the rate, while non-deductible expenses raise it.
Fix: Ask whether the item increases or decreases taxable income relative to pretax income, then apply the sign.

Worked examples

Example 1

A company has a deferred tax liability of €600 million measured at a 30% rate. A law is enacted that lowers the rate to 25% for all future periods. It also holds no deferred tax assets. By how much does income tax expense change, and which way? Options for the change in expense: (A) a €100 million decrease, (B) a €100 million increase, (C) a €150 million decrease.

Show the solution

Temporary difference = 600 ÷ 0.30 = €2,000 million.
New DTL = 2,000 × 0.25 = €500 million.
DTL falls by 600 − 500 = €100 million.
A lower DTL means lower deferred tax expense, so income tax expense falls by €100 million.
Eliminate B (wrong direction). C is the new rate times the existing liability, 600 × 25% = €150 million. That mixes a balance built at 30% with the new rate and has no meaning. The new rate must be applied to the temporary difference.

Answer: Income tax expense decreases by €100 million (A).

Example 2

A firm reports pretax income of $800 million and a statutory rate of 25%. The reconciliation shows these items as tax amounts: foreign income taxed at lower rates reduces tax by $16 million, tax-exempt interest reduces tax by $8 million, and non-deductible fines add $4 million. What is the effective tax rate? Options: (A) 22.5%, (B) 23.0%, (C) 25.0%.

Show the solution

Tax at statutory rate = 800 × 0.25 = $200 million.
The items are already tax amounts, so do not multiply them by 25% again. Net adjustment = −16 − 8 + 4 = −$20 million.
Income tax expense = 200 − 20 = $180 million.
Effective rate = 180 ÷ 800 = 22.5%, which is option A.
Check in percentage points: 25% − 16 ÷ 800 − 8 ÷ 800 + 4 ÷ 800 = 25% − 2% − 1% + 0.5% = 22.5%.

Answer: The effective tax rate is 22.5% (A). The reductions outweigh the increase, so the rate is below the 25% statutory rate.

Exam tips

Always identify whether the balance is a DTL or a DTA before deciding the sign of the effect.
Check the period of recognition. Rate changes hit tax expense when enacted.
In reconciliation questions, convert dollar items to percentage points by dividing by pretax income.
Wrong options usually reverse the sign or use cash taxes paid. Rule these out first.
When asked about forecasting, call out one-off items as non-recurring and exclude them.

Practice questions from Analysis of Income Taxes

Tax Rate Changes and Effective Tax Rate Reconciliation: frequently asked questions

What is the difference between statutory and effective tax rate?

The statutory rate is set by law. The effective rate is income tax expense ÷ pretax income. They differ because of items such as foreign income, exempt income, credits, non-deductible costs and rate changes.

How does a tax rate change affect a deferred tax liability?

A rate cut reduces the DTL, which lowers income tax expense and raises net income. A rate increase raises the DTL and increases tax expense. The effect is recognised when the new rate is enacted.

Does a rate cut always raise net income?

No. It raises net income only if the company has a net DTL. A net DTA shrinks on a cut, which raises tax expense and reduces net income.

Why do analysts read the tax rate reconciliation?

It shows why the effective rate differs from the statutory rate. This helps you decide which parts of the rate are sustainable and which are one-offs to remove when forecasting.