Roth Conversion Timing: Strategies for Couples in Their 50s with $1.5M in 401(k)s

A married couple in their late 50s, holding a substantial $1.5 million in traditional 401(k) accounts, is at a critical juncture regarding the timing of Roth conversions. Having taken over the management of their investments after experiencing significant portfolio losses with a previous financial advisor, the couple is now focused on optimizing their future tax liabilities and retirement planning. This scenario underscores the importance of individual financial strategies, particularly in light of factors like the Income-Related Monthly Adjustment Amount (IRMAA), which can significantly impact Medicare premiums in retirement.

The couple's current financial profile includes $400,000 in a taxable brokerage account and $125,000 each in Roth IRAs. Both individuals are still working and maximizing their contributions to both 401(k)s and Roth IRAs. However, one spouse’s employer exclusively offers a traditional pre-tax 401(k), limiting their ability to fully leverage post-tax Roth advantages. Their earlier decision to opt for traditional IRAs due to immediate tax deductions now makes Roth conversions a more appealing strategy for long-term tax efficiency.

Roth conversions involve moving money from traditional tax-deferred accounts into Roth accounts, which offer tax-free growth and tax-free withdrawals in retirement. The converted amount is subject to income tax in the year of conversion. The couple is considering gradually reducing their taxable cash and brokerage holdings to cover the conversion taxes, aiming to remain within the 22% federal tax bracket. Financial experts often advise paying conversion taxes from external sources rather than from the retirement accounts themselves, ensuring the full converted amount can grow tax-free within the Roth account.

Such personal finance strategies are influenced by broader economic and legislative contexts. The general expectation regarding U.S. tax policy is that taxes may trend higher over time due to federal debt and spending. While the SECURE 2.0 Act raised the age for Required Minimum Distributions (RMDs) to 73 (or 75 for those born in 1960 or later), these distributions can still push individuals into higher tax brackets during retirement. The Tax Cuts and Jobs Act (TCJA) tax rates, made permanent in 2025 by the One Big Beautiful Bill Act (OBBBA), suggest federal rates may remain stable, but individual tax rates could still increase due to RMDs.

Analysts and financial planners frequently highlight that the 50s can be an opportune time for Roth conversions. The years leading up to retirement, particularly before RMDs begin and when income might be relatively lower, present a valuable “conversion window” to capitalize on tax advantages. This strategy not only helps in managing future RMDs but can also reduce exposure to IRMAA, which affects Medicare premiums. Certified Financial Planners (CFPs) emphasize the importance of personalized tax planning to determine the optimal conversion amount and to navigate potential pitfalls.