Chapter 24: The coordination puzzle: Social Security, Medicare, RMDs

Retirement runs on three government systems: Social Security, Medicare, and required minimum distributions. They were not designed to be optimized one at a time. Claim Social Security without thinking about taxes, and you may shrink it. Do a clever Roth conversion without checking Medicare, and your premiums jump two years later. The households that do best treat ages 59½ through 75 as one chessboard. This chapter gives you the pieces and the worked example of Carlos and Elena playing them in order.

Social Security: the claiming decision

Your benefit is computed from your 35 highest-earning years (adjusted for wage growth). The formula is progressive (it replaces a bigger share of a smaller paycheck), and the result is your benefit at full retirement age (FRA), which is 67 for everyone born in 1960 or later.

Then comes the only Social Security decision most people actually control: when to claim, anywhere from 62 to 70. The math is mechanical:

• Claim at 62 and the check is cut 30%: you get 70% of your full benefit, permanently.
• Wait past FRA and the check grows 8% per year until 70, landing at 124%.

Put real numbers on it. Carlos's full benefit at 67 is $2,800 a month. At 62 it would be $1,960. At 70 it's $3,472, a gap of $1,512 a month, every month, for life, with inflation adjustments on top. The crossover where waiting pulls ahead in total dollars lands around the early 80s; live past that, and delay wins by more every year. But the deeper point is less the bet on the average than the insurance against the expensive outcome, which is living long.

Try the trade-off with your own numbers in the claiming calculator:

Working while claiming early? The earnings test applies before FRA: in 2026, $1 of benefits is withheld for every $2 you earn above $24,480 (a gentler test allows $65,160 in the year you reach FRA, and there's no test at all from the month you reach it). If Elena claimed at 63 while earning $30,480 part-time, she'd be $6,000 over the limit and $3,000 of benefits would be withheld that year. Crucially, withheld is not lost: at FRA, Social Security recalculates and credits back the withheld months as a higher ongoing benefit. Still, the test is a good reason not to claim early while you're still working much.

The survivor logic: why the higher earner waits. When one spouse dies, the survivor keeps the larger of the two checks, one check, not two. So the higher earner's delay isn't really about him; it's longevity insurance for whichever spouse lives longer.

Medicare: the deadline with teeth

Medicare is federal health insurance starting at 65, in parts:

• Part A (hospital): premium-free for most people; in 2026 the inpatient deductible is $1,736 per benefit period.
• Part B (doctors, outpatient): the 2026 standard premium is $202.90 a month, with a $283 annual deductible.
• Part D (prescription drugs): bought from private insurers, premiums vary.

The system's sharpest edge is the calendar. Your initial enrollment period is 7 months: the 3 months before your 65th-birthday month, that month, and the 3 after. Miss Part B without qualifying employer coverage and the penalty is brutal arithmetic: roughly 10% added to the premium for every full 12-month period you were late, usually permanently. Skip three years and you pay about 30% extra (around $61 a month, $730 a year at 2026 rates) for the rest of your life. Part D has its own penalty, accruing monthly after just a 63-day gap in drug coverage. (If you're still working at 65 with solid employer coverage, you can usually delay penalty-free, but verify your coverage counts before your window closes, not after.)

One more Medicare surprise matters for planning. IRMAA (income-related monthly adjustment amount) adds premium surcharges to Parts B and D for higher-income retirees, based on your tax return from two years earlier. IRMAA works like a hidden marginal tax with cliff edges: one extra dollar of income can bump your premium tier. Remember the two-year lookback; it's about to collide with the Roth conversion strategy below.

RMDs: the government wants its tax back

Traditional 401(k) and IRA dollars were never tax-free, only tax-deferred. Required minimum distributions (RMDs) are when the bill comes due: mandatory annual withdrawals starting at age 73 if you were born 1951–1959, or 75 if born 1960 or later (Carlos and Elena are both in the 75 club). The calculation is one sentence: divide last December 31's balance by an IRS life-expectancy factor. If Carlos's traditional accounts grow to $800,000 by 75, his first factor is 24.6, which works out to a required withdrawal of about $32,500, all taxed as ordinary income, whether he needs the cash or not.

Roth IRAs have no lifetime RMDs for the owner, and under current rules workplace Roth accounts are exempt too. That asymmetry is the engine of the next section.

The conversion window: the quiet years are valuable

Look at Carlos and Elena's tax timeline. Paychecks stop at 64. Social Security (Carlos's, the big one) starts at 70. RMDs start at 75. In between sit years where their taxable income is just a $27,600 pension, the lowest tax bracket they will ever see again.

A Roth conversion (moving money from a traditional IRA to a Roth and paying income tax on it now) is how you harvest those years. In 2026, a married couple can have $100,800 of taxable income and stay inside the 12% bracket; add the $32,200 standard deduction and the pension, and Carlos and Elena could convert on the order of $100,000 a year at 12% or less, money that would otherwise come out at 22%+ once the pension, two Social Security checks, and a $32,500 RMD stack up after 75. Converted dollars also stop compounding the future RMD problem and pass to heirs tax-free.

But this is exactly where optimizing one system backfires, because conversions are income, and income touches everything:

• IRMAA, two years later. Conversions at 63+ count toward the income that sets Medicare premiums at 65+.
• Social Security taxation. Once benefits start, extra income drags more of each check into taxable territory.
• Health-insurance subsidies. Elena is 62; if she's buying marketplace coverage until Medicare, conversion income directly cuts her premium subsidy. A "12% conversion" can effectively cost much more.

Their actual best plan wasn't obvious from any single year's tax return: modest conversions while Elena needs subsidized coverage, larger ones in the window after she turns 65 and before benefits and RMDs stack up, tapering as 75 approaches. They found it by modeling a decade at a time, and both survivor scenarios, since the survivor files single, in higher brackets, with the same RMDs.

Key takeaways

• Claiming age is the big Social Security lever: 62 pays 70% of your full benefit, 70 pays 124%. The higher earner's delay is survivor insurance, since the survivor keeps only the larger check.
• Benefits withheld by the earnings test ($24,480 in 2026 below FRA) are recalculated back later: withheld, not lost.
• Medicare's 7-month window has teeth: the Part B penalty is about 10% per 12 months late, usually permanent; Part D's accrues after a 63-day gap; IRMAA surcharges look back two years at your income.
• RMDs start at 73 (born 1951–1959) or 75 (born 1960+): last year-end balance divided by an IRS factor, taxed as ordinary income. Roth accounts are exempt.
• The years between your last paycheck and your first benefit check are prime Roth-conversion territory, but model several years and both lifetimes, because conversions ripple into IRMAA, benefit taxation, and subsidies.

Sources: SSA: Benefit reduction for early retirement · SSA: Delayed retirement credits · SSA: Working while claiming · Medicare: Medicare costs · Medicare: Avoid penalties · IRS: RMD FAQs