Smart retirement-savings strategies can save a lot of taxes, if you can take advantage of them. But doing so often requires predicting your future tax bracket, which is a guessing game. The key is to balance traditional pre-tax accounts with Roth after-tax accounts to hedge against uncertainty.

For example, if you expect to be in a lower tax bracket in retirement, traditional 401(k)s and IRAs are beneficial because you get a deduction now and pay taxes later at a lower rate. Conversely, if you expect higher taxes later, Roth accounts—funded with after-tax dollars—allow tax-free withdrawals.

However, tax rates and brackets are subject to change, making predictions risky. A common strategy is to diversify your tax exposure by contributing to both traditional and Roth accounts. This way, you can withdraw from the most tax-efficient source each year.

Another tactic is to consider Roth conversions, converting traditional IRA funds to Roth in low-income years, paying taxes now to avoid higher taxes later. But this requires careful planning and a long-term view.

Ultimately, there's no perfect answer, but spreading your bets can help you avoid costly mistakes.