When computing the present value, the before tax return of 8% is converted to an after-tax return - should we always use after tax return when running a time value of money question related to required returns/investable base?
Use after tax if all your other data fields are after tax. Use before tax if your data fields are before tax. Use real values if your other data fields are real values. Use nominal values if your other data fields are nominal values.
Do not mix and match.