If adding the RMD did not make the Social Security income fully 85% taxable, you might want to consider distributions from the 401(k) of more than your RMD. As additional income causes and equal amount of Social Security income to become taxable (until 85% of Social Security income is taxed), your marginal tax rate is 1.85 times your tax bracket rate. Once 85% of Social Security income is taxed, your marginal tax rate drops back down to your tax bracket rate (ignoring other things that might affect your marginal tax rate, but the results of your what-if scenario doesn't seem to suggest any). Over the long term, you might find that you pay less in taxes by taking out more over fewer years than if you limit your distributions to just the RMD over more years. Also, tax brackets are scheduled in 2026 to revert to previous higher levels. For amounts that you don't need to spend, you could directly roll the amount in excess of your RMD over to a Roth IRA rather than simply taking a regular distribution.
