Straight-line depreciation is $12,675 / 5 = $2,535.
Financial statement income is $7,192 ? $2,535 = $4,657.
Accelerated depreciation is $12,675(0.35) = $4,436 in years 1 and 2 and $12,675(0.3) = $3,803 in year 3.
Taxable income is $7,192 ? $4,436 = $2,756 in years 1 and 2 and $7,192 ? $3,803 = $3,389 in year 3.
At the old tax rate of 41%:
Deferred Tax liability for year 1 = $779.41 [($4,657 ? $2,756)(0.41)]
Deferred Tax liability for year 2 = $779.41 [($4,657 ? $2,756)(0.41)]
Deferred Tax liability for year 3 = $519.88 [($4,657 ? $3,389)(0.41)]
Deferred tax liability at the end of year 3, before the change in tax rate, is $2,079 = ($779.41 + $779.41 + $519.88)
At the new tax rate of 31%:
Deferred Tax liability for year 1 = $589.31 [($4,657 ? $2,756)(0.31)]
Deferred Tax liability for year 2 = $589.31 [($4,657 ? $2,756)(0.31)]
Deferred Tax liability for year 3 = $393.08 [($4,657 ? $3,389)(0.31)]
Deferred tax liability at the end of year 3, after the change in tax rate, will be $1,572 = ($589.31 + $589.31 + $393.08)
The deferred tax liability will decrease by $507 = ($2,079 ? $1,572) due to the new lower tax rate. An adjustment of $507 in tax expense will result in increase in net income by the same amount $507.
Another way of answering this question is as follows:
The deferred tax liability is the cost of the oven multiplied by the difference in the amount of depreciation at the end of year 3 between accelerated depreciation (100%) and straight line (60%) depreciation methods multiplied by the tax rate ((12,675 × 0.4) × 0.31 = $1,572).
The change in net income due to the change in tax rates is the cost of the oven multiplied by the difference in the amount of depreciation at the end of year 3 multiplied by the difference in tax rates (12,675 × 0.4 × (0.41 ? 0.31) = 507).