Answer:
a.) increased the after-tax cost of debt
Explanation:
Missing options are:
a.) increased the after-tax cost of debt
b.) did not change the after-tax cost of debt
c.) increased the value of the deduction for interest expense
d.) decreased the after-tax cost of debt
The after tax cost of debt is calculated by multiplying the debt's principal x interest rate x (1 - tax rate). If the tax rate decreases, the after tax cost of debt increases. e.g.
$1,000 owed at 6%, when tax rate was 40% ⇒ after tax cost of debt = $1,000 x 6% x (1 - 40%) = $36 or 3.6%
now, $1,000 owed at 6%, when tax rate is 21% ⇒ after tax cost of debt = $1,000 x 6% x (1 - 21%) = $47.40 or 4.74%
