Mainstreet Financial Education · Tax Year 2026
While you work, one paycheck fills the tax brackets from the bottom up and withholding is automatic. In retirement you draw from several sources in the order you choose, and that mix often decides your tax bill as much as the total does.
The difference is control. As a worker, the system stacked your income for you. As a retiree, you decide which dollar comes from where, and small differences in that order can change what you keep.
Three interactions catch retirees most often. None of them are obvious from a single account statement, because each one is triggered by the interaction between sources.
As your other income rises, more of your Social Security becomes taxable, up to 85% of the benefit. A withdrawal that looks like it should be taxed once can effectively be taxed twice, because it also drags benefits onto the return.
Ordinary income fills the low brackets first. Long-term capital gains stack on top. Take a large IRA withdrawal and it can push gains that would have been taxed at 0% up into the 15% rate instead.
Cross a Medicare income line by even $1 and your Part B and Part D premiums rise for the whole year. It is a cliff, not a ramp, so a single extra dollar of income can cost far more than a dollar.
How much of your Social Security is taxed depends on "combined income," which is your adjusted gross income plus any tax-exempt interest plus half of your benefits. These thresholds are set in statute and are not adjusted for inflation.
Because these dollar figures never rise with inflation, a benefit that escaped tax years ago slowly gets pulled in as cost-of-living increases lift the benefit itself. The thresholds stay still while the income moves.
In retirement, the mix of income sources often matters as much as the amount of income itself. Two retirees with identical total income can owe very different taxes depending on where each dollar came from and the order it was drawn. Deciding that order on purpose, year by year, is the heart of tax-smart withdrawal planning.
The order you withdraw is a decision, not a default.
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