Tax diversification: how different tax treatments trade off

Most retirement savings sit in one of three tax treatments. Pre-tax accounts were never taxed and will be taxed on withdrawal. Roth accounts were taxed already and generally are not taxed again. Taxable accounts are taxed as they generate income and gains.

Holding all three creates optionality. In a year with unusually high income, withdrawals can lean on the already-taxed sources. In a low-income year, the pre-tax bucket can be drawn down or converted at a lower marginal rate.

A household with nearly everything in one bucket has far less room to manage the timing of taxable income. That constraint tends to surface at two moments: the first years of retirement before Social Security begins, and the year required distributions start.

Nothing here suggests a particular balance is right for anyone. It explains why the question is asked before a specific answer is proposed.