📖 所得税：税率变化影响

Financial Statement Analysis

I. Lesson Focus

This lesson examines how enacted changes in corporate income tax rates affect the measurement of existing deferred tax assets (DTA) and deferred tax liabilities (DTL), the current-period income tax expense, the effective tax rate (ETR), and ultimately reported net income and key financial ratios. Candidates must master the directional impact of rate changes on taxable versus deductible temporary differences and be able to compute the one-time gain or loss that flows directly through the income statement.

II. The Problem

A manufacturing company begins the year with a deferred tax liability balance of RMB 1.8 million related to taxable temporary differences that are expected to reverse over the next five years. In April, the government unexpectedly reduces the corporate income tax rate from 25% to 20%, effective 1 July. The company reports pre-tax accounting profit of RMB 12 million for the year and originates an additional RMB 3 million of taxable temporary differences. How should the existing DTL be remeasured? Will the rate change increase or decrease current-period income tax expense? How will the effective tax rate change, and what is the direct impact on net income and ROE? These are the practical questions addressed in this lesson.

III. Mechanism of Tax Rate Changes on Deferred Taxes

Under both IFRS and US GAAP, when a tax rate change is enacted or substantively enacted, an entity must immediately remeasure all recognized deferred tax assets and liabilities using the new tax rate. The difference arising from remeasurement is recognized in income tax expense in the period of the change (unless the original temporary difference was recognized in OCI).

Core formula: $$ \text{Effect of rate change} = (\text{New rate} - \text{Old rate}) \times \text{Beginning balance of temporary differences} $$

• For taxable temporary differences (create DTL), a rate decrease reduces the DTL and therefore reduces income tax expense (increases current profit).
• For deductible temporary differences (create DTA), a rate decrease reduces the DTA and therefore increases income tax expense (decreases current profit).

The directions are exactly opposite, which is one of the most tested conceptual traps.

IV. Effective Tax Rate (ETR) Decomposition

$$ \text{ETR} = \frac{\text{Income tax expense}}{\text{Pre-tax accounting profit}} $$

Income tax expense = Current tax + Deferred tax

Deferred tax includes both the effect of originating or reversing temporary differences during the period and the one-time remeasurement effect caused by the rate change. A declining statutory rate often produces a significantly lower ETR for companies with large DTL balances, boosting reported net income. Analysts must separate this non-recurring benefit from sustainable operating performance.

V. Classification of Temporary Differences and Rate Sensitivity

• Taxable temporary differences: Will result in taxable amounts in future periods → give rise to DTL. Rate decreases are beneficial.
• Deductible temporary differences: Will result in amounts that are deductible in future periods → give rise to DTA. Rate decreases are detrimental.
• Valuation allowances must also be remeasured at the new rate.
• The rate used must be the one that has been enacted or substantively enacted by the reporting date; proposed but unenacted rates are ignored.

Worked Cases

Case 1: Rate Decrease on DTL (Basic)

Company A begins the year with taxable temporary differences of RMB 8 million. At the old 25% rate the DTL is RMB 2 million. During the year the rate is reduced to 21%. No new temporary differences arise.

Remeasured DTL = 8m × 21% = RMB 1.68 million
Rate-change gain = 2m – 1.68m = RMB 0.32 million (reduces tax expense)

Assume pre-tax accounting profit = RMB 10 million and current tax payable (calculated at the new rate) = RMB 2.1 million.
Income tax expense = 2.1m – 0.32m = RMB 1.78 million
ETR = 1.78m / 10m = 17.8% (well below the new statutory rate of 21%).

Case 2: Rate Increase on DTA (Opposite Direction)

Company B begins the year with deductible temporary differences of RMB 5 million, producing a DTA of RMB 1.25 million at 25%. The rate is increased to 30%.

Remeasured DTA = 5m × 30% = RMB 1.5 million
Increase in DTA = RMB 0.25 million → this amount increases income tax expense.

Pre-tax profit = RMB 8 million, current tax = RMB 2.4 million (8m × 30%).
Income tax expense = 2.4m + 0.25m = RMB 2.65 million
ETR = 2.65m / 8m = 33.125% (above the new statutory rate).

Case 3: Comprehensive Scenario with New Originations

Company C data: - Beginning taxable temporary differences: RMB 12 million (DTL at 25% = RMB 3 million) - New taxable temporary differences originated during the year: RMB 4 million - Pre-tax accounting profit: RMB 15 million - Rate reduced from 25% to 20% during the year

Steps: 1. Remeasure beginning DTL at new rate: 12m × 20% = RMB 2.4 million → rate-change gain = RMB 0.6 million (reduces expense). 2. Recognize DTL on new differences at new rate: 4m × 20% = RMB 0.8 million. 3. Current tax (assume taxable profit after adjustments = RMB 13 million): 13m × 20% = RMB 2.6 million. 4. Total income tax expense = 2.6m + 0.8m – 0.6m = RMB 2.8 million. 5. ETR = 2.8m / 15m = 18.67%.

The RMB 0.6 million rate-change gain directly increases net income and ROE.

Traps

Key Formulas

• Effect of rate change on tax expense = (New rate – Old rate) × Beginning net temporary differences
• ETR = Income tax expense / Pre-tax accounting profit
• Remeasured DTL (or DTA) = Temporary difference balance × New enacted tax rate
• Income tax expense = Current tax + Change in deferred tax (including rate-change component)
• Impact on net income = – (Effect of rate change on tax expense)

Practice Questions

Q1. When the tax rate decreases, a company with large taxable temporary differences will most likely:
A. Increase current-period income tax expense
B. Decrease current-period income tax expense
C. Have no effect on income tax expense
D. Increase deferred tax assets

Q2. Using the data from Case 1 (pre-tax profit RMB 10 million, rate change 25% to 21%, beginning taxable temporary differences RMB 8 million, no new differences), the ETR is closest to:
A. 21.0%
B. 17.8%
C. 25.0%
D. 18.4%

Q3. An increase in the tax rate on deductible temporary differences will:
A. Decrease income tax expense
B. Increase income tax expense
C. Decrease deferred tax liabilities
D. Have no effect

Q4. Which of the following does not require remeasurement at the new tax rate?
A. Beginning deferred tax liability
B. Beginning deferred tax asset
C. Existing valuation allowance
D. Current-period permanent differences

Q5. A company reports pre-tax profit of RMB 5 million, current tax of RMB 1.1 million, and an additional RMB 0.15 million tax expense from a rate change. Its ETR is closest to:
A. 22%
B. 25%
C. 19%
D. 28%

Q6. If a tax rate change has been proposed but not yet enacted or substantively enacted, the company should:
A. Adjust DTA and DTL immediately using the new rate
B. Continue using the old rate
C. Disclose only in the notes
D. Use a weighted-average rate

Q7. The positive impact on reported net income from a tax-rate reduction is usually greatest for companies that have:
A. Large deductible temporary differences
B. Large taxable temporary differences
C. No deferred tax balances
D. Tax-loss carryforwards with full valuation allowances

Q8. In Case 3, the direct effect of the rate reduction on current-period net income is:
A. Decrease of RMB 0.6 million
B. Increase of RMB 0.6 million
C. No effect
D. Increase of RMB 0.8 million

Answers

Takeaways

• Tax rate changes require immediate remeasurement of all existing DTA and DTL at the new enacted rate, with the difference recorded in current income tax expense.
• Rate decreases benefit companies with net DTL positions and harm those with net DTA positions.
• The ETR can fluctuate sharply due to rate changes; analysts must isolate the non-recurring component.
• Current tax is calculated at the new rate; deferred tax includes both origination/reversal and the rate-change effect.
• Valuation allowances are remeasured in tandem with gross deferred taxes; permanent differences are unaffected.
• The entire rate-change impact is a current-period event and does not require retrospective restatement of prior financial statements.