BOSTON ( TheStreet) -- The government's upcoming repeal of income caps for Roth IRAs could help rich Americans cut taxes on retirement savings, but few investors realize it. Beginning Jan. 1, people who make more than $100,000 will be able to move assets into Roth accounts for the first time since the investment vehicles were created 10 years ago. Almost nine out of 10 investors are unaware of the opportunity, according to a Fidelity Investments survey of 800 retirement plan owners released last week. Half of the survey participants reported household incomes of more than $100,000 a year. Unlike assets in traditional IRAs, money held in Roth accounts grows tax-free. Post-retirement withdrawals also aren't taxed. The downside is that investors don't reap the tax deductions of traditional IRAs. Lifting income limits will make it easier for affluent investors to convert assets from traditional accounts and 401(k) plans to Roth IRAs. The government will tax the assets, but the hit can be spread over two years. Among those questioned by Fidelity, 55% were considering a Roth IRA conversion, but only 7% planned to shift assets in the near future. Many said they were unaware of the process, with one-third saying they didn't understand a Roth conversion's tax implications. When asked whether contributions are tax deductible, 28% answered incorrectly. Twenty percent didn't know that assets in Roth accounts aren't taxed, and 32% didn't know that funds can be withdrawn tax-free after age 59 1/2. More than half didn't realize Roth funds could be used for first-time home purchases and college costs.