Roth IRAs provide tax-free growth. Your non-deductible IRA contribution grows tax-free and qualified withdrawals are not taxed. This strategy allows younger investors to potentially grow their investments over the long term. Traditional IRAs provide tax-deferred growth. Any income your IRA investments earn will not be taxed until you start taking distributions from the account. This is a popular strategy for those who expect to be in a lower tax bracket when they retire.