A worked example

What the tax code does to whoever is left

Ellen and Ray, both 72, retired with $1,800,000 in pre-tax accounts, $150,000 in Roth accounts, and a $400,000 brokerage account, spending $130,000 a year. Their combined Social Security is $70,000; if one of them dies, the survivor keeps the larger check, $44,000, and the other stops.

“If one of us outlives the other by a decade, what does that do to the taxes on the same money?”

What the projection shows

Two runs of an identical plan with the same accounts and the same required withdrawals. The only difference is who files the tax return. The year of the death is still a joint return. From the year after, the survivor files single, which halves the standard deduction and every bracket, and pulls the Medicare (IRMAA) thresholds down with them. The compare view puts each year next to its twin: taxable income that is lower, tax on it that is higher, and surcharge years the couple never had. None of this is a recommendation. It prices something that happens to most married households, so it's in the plan rather than a surprise for whoever is left.