QuantCalc Research

When to claim Social Security if the 2033 reduction happens: 62 vs 67 vs 70

Under the 2026 Trustees projection (78% of scheduled benefits payable from 2033), the lifetime-value-maximizing claiming age falls from 70 to 68 in the base case across 18 profiles, and the classic 62-vs-70 break-even stretches from age 80 to 82. Includes an after-tax and tax-torpedo view.

What a 22% Social Security cut does to retirement success: a 10,000-path Monte Carlo study

When half of income comes from Social Security, a 2033 reduction is a 15.3-point fall in success rate for a 60/40 retiree — offset by roughly $122,768 more saved. Modeled across three allocations and three reliance levels, per the 2026 Trustees Report (ssa.gov/oact/trsum/, checked 2026-09-10).

What crossing an IRMAA tier costs a Roth conversion: 2026, tier by tier

The Medicare surcharge is a fixed-dollar cliff two years later, so a small conversion that just clips a new tier is punished hardest per dollar. This study prices the first dollar over every 2026 tier, the room to the next one, and when crossing still beats leaving the money for future RMDs.

Withdrawal strategy success rates: guardrails vs. the fixed 4% rule, quantified

Four withdrawal rules — the static 4% rule, a constant 5%-of-balance rule, Guyton-Klinger guardrails, and Variable Percentage Withdrawal — run on the same 10,000 Monte Carlo paths over 35 years. The guardrail plan cuts the 4% rule’s failure rate from 17% to 1.1% — a 94% reduction, by trading depletion for spending cuts — at about 40% less median legacy.

The 2026 ACA subsidy cliff for early retirees: an 80,000-path Monte Carlo study

Modeling a 55-to-65 healthcare bridge with 2026 tax and ACA parameters, the study measures what the subsidy cliff costs a retiree who does not manage MAGI — and how much a tax-optimized withdrawal order recovers.

Social Security at 70 beats 62 only 42% of the time — if you invest

A 400,000-life Monte Carlo over real mortality (SSA 2021 Period Life Table) and real investment returns shows the famous age-80 break-even hides a coin flip: at a balanced 4% real return, delaying wins 42% of lifetimes; at an equity-tilted 6% real return, only 28% for men.

Retiring into a bear market: same plan, 46% failure vs. 0%

A 50,000-path block-bootstrap Monte Carlo of U.S. historical returns (1928–2024) isolates sequence-of-returns risk by holding the plan fixed and only reordering the first decade. A reversed 1973–2002 sequence with the identical average return leaves 6× more terminal wealth than the forward order.

Does the 4% rule survive forward-looking forecasts? Six published CMEs stress-tested

10,000-path Monte Carlo simulations of a classic $1M, 60/40, 4% inflation-adjusted withdrawal with no other income, run under six publicly-published Capital Market Expectations. Against a 95.9% historical baseline every forecast lands lower, and among the survivors median terminal balance spans 2.3× — a plan’s safety margin depends heavily on which return assumption it borrows.

The lifetime tax cost of skipping Roth conversions in the gap years

A deterministic federal-tax simulation (2025 MFJ brackets, SECURE 2.0 RMD age 73) compares doing nothing with a Traditional IRA against filling the 12% bracket with Roth conversions before RMDs start. A $500,000 IRA can lose money converting — the benefit scales with balance size.

Do alternative assets actually improve retirement outcomes? 60,000 Monte Carlo paths on gold, commodities, TIPS & bitcoin

60,000 paths through the same engine as the live calculator test gold, commodities, TIPS, and a small bitcoin sleeve against a standard 5-asset portfolio. TIPS lower success at this withdrawal rate; bitcoin’s headline gain traces back to its assumed return, not diversification.

510,000 retirement Monte Carlo paths across all 51 U.S. jurisdictions: the state-tax cost of retirement in 2026

The same representative retiree (age 60, $2M, 60/40 portfolio, $80K real annual spend) runs through 10,000 Monte Carlo paths in every state plus DC, changing only the state tax code. Wyoming, Louisiana, and South Dakota cluster at the top; California, DC, and New York rank worst.

When does tax-loss harvesting actually pay? NPV across 768 scenarios

Every scenario runs through the same open, unit-tested 2026 federal tax engine as the free calculator, computing exact with-versus-without differences rather than marginal-rate shortcuts. Short-term-gain offsets save 1.71× more than long-term offsets at the top income level tested.

Roth Conversion Breakeven by State (2026)

A traditional→Roth conversion costs the same federal tax everywhere, but the state slice of the bill varies wildly by jurisdiction. This study runs a 1,224-scenario sweep across all 51 U.S. jurisdictions to price the state, federal, and combined cost of converting — and the future tax rate above which converting today wins.

The 4% rule across 123 historical retirement cohorts

A rolling-cohort study of every U.S. retirement start year with a full 30-year window in the Shiller dataset (ie_data.xls, checked 2026-09-10), computing the maximum sustainable withdrawal rate and survival at 4.0/4.5/5.0% for 60/40, 50/50, and 80/20 portfolios. Historical results, not a forecast — a companion to the CME stress test above.

The 2026 IRMAA Cliff Map

Maps every 2026 Medicare IRMAA tier boundary for single and MFJ filers — the surcharge just below vs. at each cliff, the cost of the single dollar that crosses it, and the headroom to the next one. Distinct from and cross-linked with the companion Roth-conversion IRMAA cost study above.

The 2026 OBBBA Senior Deduction, Decomposed

A retiree’s 2026 standard deduction is three deductions stacked together: the base standard deduction, the IRC §63(f) additional deduction for the aged, and the temporary OBBBA §70103 senior deduction. This study decomposes the stack by filing status, age, and MAGI, and maps exactly where the $6,000-per-filer OBBBA piece phases out to zero.

The Optimal Retirement Glide Path (2026)

Should a retiree’s equity allocation glide down, hold flat, or rise? This study hands the whole 5-period schedule to QuantCalc’s optimizer at 3.5% / 4.0% / 4.5% withdrawal rates, then independently re-scores its choice against static 60/40, static 40/60, declining 70→30, and rising 30→70 schedules on common random numbers — reporting a winner only when it beats the sampling noise.

The ACA Bridge Income Plan (2026)

How much income should an early retiree realize — and how much traditional balance to convert to Roth — before Medicare, without crossing the 400% FPL cliff? This study gives six households a recommended year-by-year plan with its per-year coverage regime, against never converting and against a plan that fills the 12% bracket and ignores the cliff.

When Withdrawal Order Helps, and When It Backfires (2026)

Which order saves the most lifetime tax, household by household? For nine households this study names the recommended whole-retirement order and its paired per-path present-value saving against traditional-first, reports what the single-year lowest-tax order would have cost or saved beside it, and shows a horizon sweep where the single-year order's benefit inverts into a cost.

Where Retirement Income Is Actually Taxed: the State Pension-Exclusion Map (2026)

Which states exempt or cap pension income versus IRA and 401(k) distributions, at what age, and where the pension SOURCE (government vs private) changes the bill. All 51 jurisdictions grouped by treatment, with the exclusion shown in dollars, computed from the frozen state-tax engine.

Roth Conversion Breakeven by Age (2026)

When does paying Roth-conversion tax now overtake deferring, and how does the answer move with the converter's age? 756 deterministic scenarios across conversion ages 55–75, three bracket targets, three growth rates, and four final marginal rates — with the SECURE 2.0 RMD seam (73 vs 75) and the IRMAA lookback computed from the same parity-tested engine as the by-state companion study.

The Cost of Delaying Medicare Enrollment (2026)

What does delaying Medicare enrollment actually cost? The permanent Part B penalty (10% of the $202.90 standard premium per full 12-month period) and Part D penalty (1% of the $38.99 national base premium per uncovered month) computed for every delay from 0 to 120 months and priced into lifetime cost streams at ages 85, 90, 95 and an IRS life-expectancy horizon — with the creditable-coverage paths that make a delay free, and the COBRA seam that does not.

Municipal Bond Interest and the Social Security Tax Torpedo (2026)

Municipal-bond interest is federal-tax-free as income but counts in three statutory income tests: Social Security provisional income (IRC §86(b)(2)(B)), IRMAA MAGI and ACA MAGI. 984 scenarios across both filing statuses, three benefit levels, an income sweep and four muni levels compute the muni dollar's four regimes (0 → 0.50× → 0.85× bracket → 0 at the ceiling), the torpedo-window edges, the IRMAA tier jumps and the 400% FPL cliff — through the same engine as the live torpedo calculator.

The Widow's Penalty: the Survivor Filing-Status Change (2026)

When one spouse dies, the survivor keeps most of the income — the larger Social Security check, the pension, the RMDs — but files single after the year of death (IRC §6013(a)(3); the §2(a) qualifying-surviving-spouse extension requires a dependent child and rarely applies to retirees). 488 scenarios compute the before/after: the standard deduction and bracket edges halve, IRMAA thresholds halve (42 U.S.C. §1395r(i)(2)(B)), the §86(c) thresholds drop, and each household's change is decomposed into a filing-status penalty and an income effect — through the same engine as the live widowhood calculator.

Qualified Charitable Distributions: the AGI Exclusion vs the Charitable Deduction (2026)

A retiree 70½+ can give the same dollars three ways: a qualified charitable distribution straight from the IRA (excluded from AGI under IRC §408(d)(8), counts toward the RMD, $111,000/person in 2026 per Notice 2025-67), a cash gift under the standard deduction (relieved only by the new §170(p) $1,000/$2,000 non-itemizer deduction), or an itemized cash gift under the new 0.5%-of-AGI floor. 792 scenarios compute all three — federal tax, §86 Social Security taxability, IRMAA tiers, tax saved per $1,000 given — through the same engine as the live QCD calculator; the AGI-exclusion-vs-deduction seam does all the work.

TIPS Ladder vs the 4 Percent Rule: Locked-In Real Income or Market Upside for 30 Years (2026)

Which is safer for a 30-year retirement, a TIPS ladder or the 4% rule? This study prices a 30-year ladder at three illustrative real yields — income per $1M, cost per $1 of real income, the capital that locks $40,000 real for 30 years and the residual left for equities — and sets it beside the 4% rule’s failure share and terminal wealth quoted, not re-simulated, from QuantCalc’s published forward-looking, sequence-of-returns and historical-cohort studies. A hybrid row puts essentials on the ladder and the rest at market; the two failure modes are spelled out in plain words.

Annuity or the 4 Percent Rule: Which Gives More Secure Retirement Income? (2026)

Annuity or the 4% rule — which gives more secure retirement income? This study prices a life-only immediate annuity bought at 65 at three illustrative payout rates — income per $1M, its real value in years 10, 20 and 30, the premium that covers $40,000 of first-year spending, the break-even age and an annuitise-the-essentials hybrid — reads survival to 80/85/90/95 from the SSA period life table (checked 2026-09-10) behind the site’s claiming research, and sets it all beside the 4% rule’s failure share and terminal wealth quoted, not re-simulated, from QuantCalc’s published Monte Carlo studies. Longevity and sequence risk on one side, inflation, liquidity and bequest on the other, in plain words.

Bucket Strategy vs Total Return: Does a Cash Bucket Protect a Retirement Portfolio? (2026)

Bucket strategy or total return — does a cash bucket protect a retirement portfolio? This study runs the engine’s two-bucket rule (2, 3 and 5 years of spending in cash, refilled after non-losing years or when below half) against a total-return portfolio built to hold the same starting cash, for 3.5%, 4% and 4.5% spending on 60/40 and 80/20 plans, 10,000 paired paths per arm. Success rates, median and 10th-percentile wealth at 95, and the per-path paired difference — median, band, share of paths the bucket ends higher, survival crossovers — with the gap followed year by year and the refill rules compared head to head.

Should the Lower Earner Claim Social Security Early and the Higher Earner Delay? A Household Monte Carlo (2026)

Should the lower earner claim Social Security early and the higher earner delay? This study runs every combination of 62, 67 and 70 for both spouses through the engine’s household model on identical market paths — two benefit personas ($3,000 / $1,500 and $2,500 / $800 at full retirement age), 10,000 paired paths per arm, with and without the higher earner dying at 80 — and reports success, wealth at 95, the per-path difference against claiming together at 67, the lifetime benefits each combination pays and what the survivor keeps, with the gap followed year by year.

Work One More Year or Save More: Which Moves Retirement Success More? (2026)

Work one more year or save more — which moves retirement success more? This study runs six arms against a retire-at-65 baseline on identical market paths: retire at 66 or 67, save $10,000 or $20,000 a year more for the last five working years, or spend $5,000 or $10,000 a year less — for a comfortable and a marginal persona, 10,000 paired paths per arm. Success rates, median and 10th-percentile wealth at 95, the per-path paired difference, and success gained per year worked, per $10,000 saved and per $5,000 cut, with the gap followed year by year and the mechanism spelled out in plain words.

Part-Time Income in Early Retirement: How Much Does $10,000 a Year Change the Plan? (2026)

How much does $10,000 a year of part-time income change an early-retirement plan? This study runs $10,000, $20,000 and $30,000 a year for five and ten years from 55 through the engine on identical market paths — a plan that mostly works and a tight one, 10,000 paired paths per arm — and reports success, wealth at 95, the per-path difference against not working, success gained per $10,000-year, the gap followed year by year, and the same money saved beforehand instead of earned.

Inherited IRA Under the 10-Year Rule: Spread the Withdrawals or Take a Lump Sum? (2026)

Inherited IRA under the 10-year rule — spread the withdrawals or take a lump sum? This study empties $300,000 and $600,000 inherited traditional IRAs six ways inside the SECURE Act window — lump sum, 1/N of the balance, level draw, fill the current bracket, annual RMD then year 10, nothing until year 10 — against $80,000 and $160,000 of other income, at 5% and 3% growth, through the same 2026 federal-tax, IRMAA and Single-Life-Table modules the site’s calculators run. Tax on the IRA dollars, share of the inheritance, effective rate, highest bracket reached, after-tax value nominal and discounted, and an IRMAA sub-case for a beneficiary already near Medicare, with the bracket mechanics spelled out in plain words.

Pay Off the Mortgage or Invest Before Retirement? Paired Monte Carlo Results (2026)

Pay off the mortgage or keep investing before retirement? This study runs the two choices on identical market paths for a 65-to-95 retiree with $1,000,000: a $200,000 balance with 15 years left at 4.0%, 5.5% and 6.5%, the level payment charged as a nominal constant, and $50,000, $40,000 or $30,000 a year of other spending, 10,000 paired paths per arm. Success rates, median and 10th-percentile wealth at 95, the per-path paired difference — median, mean, band, share of paths each arm ends higher, survival crossovers — followed year by year, and the break-even portfolio return found by re-running every cell across a grid of return shifts.

Bond Tent, Cash Bucket or Guardrails: Which Handles Sequence-of-Returns Risk Best? (2026)

Bond tent, cash bucket or guardrails — which handles sequence-of-returns risk best? This study runs a rising-equity glide path (40% equity at 65 to 60% or 70% by 75), the engine’s two-bucket cash reserve (3 and 5 years, with matched-cash controls) and Guyton-Klinger guardrails against a constant 60/40 level-spending control on the same 10,000 paths, for 3.5%, 4% and 4.5% spending. Success, wealth at 95, the per-path paired difference, realised spending path by path, and every figure cut by decile of first-decade return — with what each defence changes and what it costs in plain words.

Your 30-Year Plan Is Built on a 7-Year Forecast: What the Horizon Mismatch Costs (2026)

Capital market assumptions are published over 7, 10, 20 and 30 years; retirement plans run 30. This study runs one plan 5 ways twice on 10,000 paths per arm — each forecast stretched across all 30 years, then applied only for the years its publisher forecasts with a 30-year set thereafter — and reports what the difference is worth in success rate and terminal wealth. It is the general form of a correction to our own 4% rule stress test.