The Roth 401(k) for retirement

The Roth 401(k) has been slowly growing in popularity since its creation in 2006. According to this WSJ article, over 80% of employer retirement plans now offer these. In this article, we will discuss this relatively new way to accumulate retirement savings and the trade-offs made when using one.

Roth 401(k) plans continue to grow.

Pay taxes now or later

Employers that offer both traditional 401(k) and Roth 401(k) plans give employees greater control over when taxes are due on their retirement savings. An employee can defer taxes on retirement contributions with a traditional 401(k) plan. These contributions will likely reduce their current taxable income and consequently the amount of taxes owed during each working year. Additionally, gains in a traditional 401(k) plan grow tax-deferred. However, ordinary income taxes are generally due on future withdrawals or on Roth conversions of these tax-deferred plan assets rolled into an IRA.

Conversely, when an employee contributes to a Roth 401(k), there is no tax-deferred benefit. Instead, the contributions are part of their current year’s income. However, once the funds are in the Roth 401(k), like in a Roth IRA, the funds grow tax-free. Additionally, qualified withdrawals during retirement are generally tax-free.

Pros and Cons of a Roth 401(k)

Retirees gain the most obvious benefit from a Roth 401(k) when future taxes are higher. For example, if the Tax Cuts and Jobs Act (TCJA) from 2017 expires at the end of 2025 without the U.S. Congress intervening, tax rates will revert to pre-2017 levels, which are higher than current rates. Additionally, younger workers who expect significant wage growth may also benefit from the Roth 401(k). And, if there are unexpected large expenses in retirement, having some after-tax funds can help retirees avoid spikes in taxable income.

If you are not sure how much to contribute to a Roth 401(k), you can follow research by David Brown, an associate professor of finance at the University of Arizona. His research suggests a rule of thumb where you add 20 to your age and put that percentage into a traditional 401(k), with the rest in a Roth 401(k). For example, a worker who is 45 should put 65% of their 401(k) savings in pre-tax contributions, and the remaining 35% as after-tax Roth 401(k) contributions.

Our software may help

We offer two online software tools to help in this planning decision. The first can predict future retirement savings balances across tax-deferred, tax-exempt, and taxable accounts based on future contribution amounts. The second can predict the longevity of your portfolio, or what your non-spouse heirs may expect for an inheritance, based on the U.S. progressive tax system. We encourage you to use tools like these to better understand savings decisions made today to meet your future retirement goals.

ETFMathGuy is a subscription-based education service for investors interested in using commission-free ETFs in efficient portfolios.
ETFMathGuy is a subscription-based education service for investors interested in tax-efficient investing with ETFs

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