Picture the household. Both spouses retire at 63. Social Security is deferred to 70 for the survivor benefit. Portfolio is $1.4M, most of it in a Traditional IRA. Between 63 and 73, their taxable income is minimal — a little dividend income, a little pension. Their marginal bracket is 12%.

This is the ten-year window. And most people use it to do nothing.

What they should be doing is converting a chunk of the Traditional IRA to Roth every year — enough to fill the 12% bracket and stop cleanly before the 22% jump. Over ten years, that's often $600K–$900K moved into a tax-free bucket at a bracket they may never see again.

Then RMDs start, Social Security starts, and their bracket walks up to 22% or 24% for the rest of their lives. But the Roth is already loaded. It grows tax-free. It gets inherited tax-free. It never has an RMD.

The people who understand this window are quietly building generational wealth. The people who don't are handing the difference to the IRS.