A 71-Year-Old Retired Federal Employee With $890,000 in a TSP Discovers His Pension Quietly Disqualified Him for the IRMAA Hold-Harmless Rule

A retired GS-13 with a solid FERS pension, a well-funded Thrift Savings Plan, and steady Social Security income would seem financially insulated from unpleasant Medicare surprises. Yet many federal retirees are caught off guard by IRMAA surcharges because they assume the Medicare hold-harmless provision protects them the same way it protects most beneficiaries. It does not, and many people only discover the difference after the higher premium has already been locked in for the year.

The issue surfaces regularly in federal retiree discussions on Reddit’s r/fednews and in Bogleheads Medicare planning threads. A common scenario involves a longtime federal employee in his early 70s who finds his Medicare Part B premiums running hundreds of dollars higher than those paid by neighbors with similar income, simply because his premiums are billed differently. On paper, the Medicare calculations look identical. The underlying legal protections are not, and that distinction is costly.

The Setup in Plain English

Our retiree is 71, single, and drawing three income streams that together stack up quickly for IRMAA purposes. He believed the hold-harmless rule would cap any year-over-year jump in his Part B premium whenever Social Security’s COLA did not keep pace with rising premiums. It is a reasonable assumption, and it is wrong for him.

• Age and status: 71, single, retired federal employee under FERS
• Guaranteed income: $48,000 FERS pension plus $32,000 Social Security
• Investment assets: $890,000 in the TSP, mostly traditional (pre-tax)
• Core issue: MAGI lands just above the $109,000 first IRMAA tier for single filers in 2026
• What’s at stake: a recurring Medicare surcharge that compounds every year he lives

Why Hold-Harmless Doesn’t Apply Here

The hold-harmless provision contains one structural requirement that many federal retirees overlook: Medicare Part B premiums must be deducted directly from Social Security benefits. Many federal retirees pay Medicare premiums separately through direct billing from CMS, while their FERS or CSRS annuity continues through OPM unchanged. That billing structure can quietly disqualify them from hold-harmless protection, even though they are paying the same Medicare premiums as everyone else.

For 2026, the standard Medicare Part B premium is $202.90 per month. Crossing into the first IRMAA bracket raises the monthly Part B premium to $284.10, with an additional Part D surcharge of $14.50 per month layered on top. For a single filer, that first IRMAA tier adds approximately $1,148 in annual Medicare costs. Reaching the second IRMAA tier pushes the combined yearly increase to roughly $2,885. CMS estimates that about 8% of all Part B beneficiaries pay an income-related amount, but that share skews heavily toward retirees with pensions and investment accounts.

The MAGI trap is the other half of the problem. His pension plus 85% of Social Security already puts him in the mid-$70,000s before any TSP distributions. Add voluntary withdrawals or required minimum distributions on an $890,000 traditional balance, and crossing the $109,000 single-filer threshold becomes nearly automatic. IRMAA uses a two-year lookback, so the income he reports in 2026 dictates his 2028 premium, making the planning window narrower than most retirees realize.

Inflation compounds the problem in a subtle way. The 2026 IRMAA brackets were adjusted by only about 1%, reflecting the CPI-U increase of roughly 1% for the 12 months ending August 2025. Meanwhile, the most recent BLS data shows the CPI-U rose 3.4% for the 12 months through July 2026. Social Security COLAs adjust on that same index, and his pension carries its own reduced COLA, but none of these forces move in lockstep with his actual cash flow. When income nudges upward faster than the brackets widen, a retiree can slip into a higher surcharge tier without making any change to his spending.

Three Moves That Change the Outcome

1. File Form SSA-44 for an IRMAA reconsideration. Retirement itself counts as a qualifying life-changing event. If his 2024 income (the year IRMAA looked back to) was inflated by a partial year of GS-13 salary plus pension, the Social Security Administration can recalculate using his current, lower income. This is the fastest dollar-for-dollar fix available, and the one most federal retirees skip because they do not know the form exists.
2. Switch Part B to direct deduction from Social Security. Enrolling in the standard withholding arrangement restores eligibility for hold-harmless protection in future years. It will not erase a current IRMAA surcharge, but it changes the structural risk going forward, particularly in years when CPI moderates and the COLA underperforms premium growth.
3. Run bracket-filling Roth conversions before RMDs begin at age 73. With $890,000 sitting in a traditional TSP, there is now a more direct path than many retirees realize. As of January 28, 2026, the Federal Retirement Thrift Investment Board finalized rules allowing participants to convert traditional TSP balances to Roth directly inside the plan, without rolling money into a separate Roth IRA first. Converting smaller amounts each year within the 22% or 24% federal bracket lowers future RMDs, which lowers future MAGI, which reduces IRMAA exposure over time. The catch is that every conversion dollar counts as taxable income in the conversion year, so the math has to be done with IRMAA bracket thresholds clearly in view before each conversion is initiated.

What to Do This Month

The first step is pulling the most recent IRMAA determination letter from the Social Security Administration and confirming which tax year was used to calculate the surcharge. If that lookback year included federal wages that no longer exist, filing Form SSA-44 along with proof of retirement can often reduce or eliminate the surcharge for the current Medicare premium year. The form is available directly from the SSA, and the agency accepts supporting documentation of the life-changing event alongside it.

The next priority is mapping out taxable income for the next several years before initiating any Roth conversions. IRMAA operates on hard income cliffs: one dollar above a threshold triggers the full higher surcharge tier for the entire year. For single filers, the key pressure points cluster around modified adjusted gross income levels near $109,000, $137,000, and $171,000. A well-managed conversion strategy aims to stay comfortably below the next threshold rather than pushing against it, using the TSP’s new in-plan conversion feature to move money in controlled, bracket-sized increments.

The long-term mistake is treating IRMAA as a temporary annoyance rather than a recurring retirement cost layered on top of Medicare. Required minimum distributions can steadily push MAGI higher over time, bumping retirees into larger surcharge tiers if no planning occurs early. In most cases, the real protection comes from proactive paperwork and carefully structured withdrawal planning, not from reacting after the premium bill arrives.

Editor’s note: This article was updated to reflect the BLS-reported CPI-U annual rate of 3.4% through July 2026, replacing an earlier figure through April 2026, and to incorporate the January 28, 2026 FRTIB rule change that now allows federal employees and retirees to convert traditional TSP balances to Roth directly inside the plan without a rollover.

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