State retirement-income tax differences

Federal IRMAA and federal income tax are only part of retirement cash-flow math. U.S. states differ sharply: some tax retirement distributions and Social Security; some partially exempt them; some have no wage income tax at all.

Moving across state lines, or splitting residency, can change effective tax on the same withdrawal — while Medicare IRMAA remains a federal construct. A spreadsheet that ignores state rules can be “correct” federally and still wrong for household cash flow.

Because state rules change and residency facts are personal, Gate 0 does not ship a state engine. Treat state tax as a required manual layer (or a later module with cited statutes) rather than something an IRMAA widget silently assumes away.

Practical habit: when you compare two withdrawal or conversion scenarios, write down federal ordinary tax, IRMAA, and state tax as three separate lines. If any line is “unknown,” label it unknown — do not fill the gap with hope.