It's hard to argue with the appeal of the Roth IRA: Sock away post-tax dollars now, then withdraw your years of accumulated growth tax-free in retirement! Unfortunately, most investors don't realize that the rules now enshrining that promise of tax-free goodness could change at any time.And on the subject of tax withholding on the year you buy your volt, if you have an option to contribute to a roth 401k (after-tax) rather than standard 401k, consider it. Contributing "before tax" reduces your taxable income, so if you fall under that $7500 threshold, you are loosing the difference. So whatever I put away this year into roth 401k is considered after tax, even though my tax bill will be near zero thanks to the credit. When I retire, the money I put in my 401K and the interest on it will be considered after-tax.
Before you laugh off that notion, remember that Social Security benefits weren't always taxable. Amendments to the Social Security Act back in 1983 introduced that wrinkle. Today, depending on your means, part or much of your Social Security benefit may be taxable income to you.
Tax rules change over time. Rates have gone up and down throughout history, on both incomes and our investments. Various credits and deductions come and go. In the Roth's case, means-testing could leave wealthier accountholders paying taxes on at least some of their withdrawals.