Delaying required IRA withdrawals can double taxable income in one year, pushing retirees over IRMAA thresholds and increasing Medicare costs.
Retirees turning 73 face a decision on required minimum distributions that could add $70,000 to their taxable income if deferred to April 1. This timing choice may push modified adjusted gross income over IRMAA thresholds, raising Medicare premiums two years later.
The first IRMAA tier increases annual Medicare costs by roughly $2,300 for couples, while the second tier can push household premiums to nearly $6,000. Only 8% of Medicare beneficiaries currently pay IRMAA surcharges, but the risk is concentrated among those near the 2026 thresholds of $218,000 for joint filers or $109,000 for singles.
IRMAA uses a two-year lookback, meaning 2026 income determines 2028 premiums. Tax-exempt municipal bond interest also counts toward MAGI, with no correction after filing. The impact is irreversible once the tax year closes.