IRA/401k contributions are pre-tax and thus tax deductible, so you need to account for that deduction in the current tax year. The income produced within the IR

IRA/401k contributions are pre-tax and thus tax deductible, so you need to account for that deduction in the current tax year. The income produced within the IRA/401k is taxed upon withdrawal. Roth IRA/401k are post-tax investments, and thus not tax deductible. And the income they produce within the IRA/401k is not taxed upon withdrawal. Ergo, traditional IRAs are more complicated because you have to account for the deduction in the current year, and you have to account for income tax (as well as FICA by the way) upon withdrawal, plus there are mandatory distribution rules based on your age. The Roth IRA are less complicated, no deduction claimed therefore no deduction to prove in the current year, and no taxes to compute on withdrawal, with no mandatory distributions.