In addition to the other answers, I would only add one explanation:
The Roth IRA and IRA conceptually both create a consumption tax system (as opposed to an income tax system), but they differ in the timing of their tax. Therefore, all other things being equal, from a purely tax-motivated perspective the IRA is better if your current tax rate is higher than your retirement tax rate. On the other hand, the Roth IRA is better if your current tax rate is lower than your retirement tax rate.
An IRA works like a 401(k) plan -- a deduction from gross income is allowed for contributions -- that is, any money you invest in an IRA is not taxed to you currently as income. For example, if you have $10K income, but invest it all in an IRA, then you have taxable income of $0 and tax of $0. (But note Yoyo's answer concerning the availability of the deduction.) If you allow the $10K to grow at 8% interest, tax-free for 20 years, you will have $46.6K interest, providing a total withdraw in year 20 of $56.6K (i.e. the original $10K and the $46.6K of interest). However, you will pay tax on the full withdraw. If your tax rate is 28%, then you pay 15.8K tax & take-home $40.8. Notice especially that what does not matter is your tax rate when you earn the original $10K.
The tax on the principal (e.g. the $10K) and on any interest it produces over the years is differed until the money is withdrawn (to be spent). Since the contribution is not taxed when it is earned, but rather when it is spent, the IRA converts the income tax into a consumption tax.
A Roth IRA is funded with post-tax dollars -- that is, there is no deduction for contributions. But after you pay the tax currently on contributions to a Roth IRA, you have "consumed" the contribution & are not taxed on it or any interest it earns ever again. For example, if you have $10K income, you will be taxed on it at your current tax rate -- say, 28% -- paying $2.8K tax and leaving $7.2K to contribute to your Roth IRA. If you allow the $7.2K to grow at 8% interest, tax-free for 20 years, you will have $33.6K interest, providing a total withdraw in year 20 of $40.8K (i.e. the original $7.2K and the $33.6K of interest). When you withdraw the funds in year 20, there is no tax, providing the same "take-home" result in the Traditional IRA example above. Notice that what does not matter is your tax rate when you retire and withdraw the funds.
If your current tax rate is higher (than your retirement rate), then it does not effect the traditional IRA at all, but in a Roth IRA, you will have less of your income to invest, providing a lower total return. On the other hand if your current tax rate is lower, then you will have more of your current income ot invest in the Roth IRA, providing a greater return. So this makes the decision easier: First, determine your expected tax rate on retirement. Second, determine the rate at which you contribution will be currently taxed. Then, pay the lower of the two rates.
Your current tax rates might (and probably will) change over time, so it may be smart for you to have both a traditional and a Roth IRA. When you are a poor student (but wise enough to invest in your retirement early), you will have a very low (if any) tax rate, so a Roth IRA is a sure thing. If you are making the big money (but wise enough not to blow it on loose living), you will have a higher tax rate, so a traditional IRA (or a 401(k) plan) may pay-off.
Comments
Right on! Couldn't have explained it any plainer.
by JosephN on May 21st, 2004
great explanation. Thanks. Pocco
by pocco on April 20th, 2009