Calculation of cost of debt (Bond)

I have question about the calculation of bond (kd):

The first way we take Coupon * (1-Tax) to be included in cash flow and then apply IRR method. The result will after-tax cost of debt (as ACCA answer)

The second way we just inlcude Coupon and the apply method to derive the kd. This kd will be multiplied with (1-Tax) to calculate after-tax cost of debt

Thank you so muc