Suppose you are a thirty-year-old worker choosing between an IRA, a ROTH IRA and a regular brokerage account. Your marginal federal tax rate is 15% now and 15% in retirement. Your investment of $1000 of reduction of current consumption will earn before tax return of 7% for 35 years (note, this means that you invest approximately $1176=$1000/(1-.15) for a regular IRA, getting back $176 as reduced taxes, in the first example, while you invest $1000 for the other two types of accounts). The tax on investment returns on a regular brokerage account is 10% (meaning you earn a 6.3% after tax annual yield).
(a) Compare after-tax returns on all three forms of investment. Rank the investment options.
(b) Suppose your tax rates are 30% now and 15% in retirement: what is the best option now? Please be sure to keep the initial decrease in consumption (aftertax income) constant.
(c) What if the rates are 15% now and 30% in retirement?
(d) Suppose the marginal tax rate now is 15%. What would future marginal tax rate have to be for a regular brokerage account to be a better option than a regular IRA?