Social Security COLA 2027: The Raise Retirees Don't Fully Keep

The 2027 Social Security COLA is 3.6%, as announced by the Social Security Administration on October 14, 2026 (SSA 2027 Cost-of-Living Adjustment (COLA) Fact Sheet). On a $2,400/month benefit, that is an extra ~$86/month. But what lands in your account is the COLA minus whatever the 2027 Medicare Part B premium turns out to be: the 2026 Part B premium rose $17.90/month (9.7%), well above general inflation, and a similar 2027 increase would claim roughly one-fifth of that raise. Retirees whose MAGI crosses an IRMAA boundary can lose far more — for them, the raise can effectively turn negative. Here is how the math actually works, and what to do about it before Medicare's October 15 open enrollment.

We recompute the 2027 COLA projection from the statutory CPI-W formula after every monthly release — see the live 2027 COLA tracker →

Where the 2027 Estimates Stand

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Here is where the estimates stood on September 11, 2026, the day the August CPI-W print landed, beside the figure SSA announced on October 14, 2026:

The August print is the headline. It came in firm — up 0.42% month over month against a five-year average August step of about +0.18% — which pushed our central case up from 3.4% to 3.5% and narrowed the band further. TSCL's 3.8% was computed before either print landed and now sits just above the band; TSCL updates after each CPI release, so expect its number to move too. CPI-W (the index that determines COLA) weights energy more heavily than the standard CPI-U, so energy swings hit COLA calculations disproportionately hard.

The September CPI-W print completed the formula, and SSA announced the official 2027 COLA of 3.6% on October 14, 2026 (SSA 2027 Cost-of-Living Adjustment (COLA) Fact Sheet). Our last projection before the announcement was 3.5%. The 2027 COLA page shows how the formula produced it.

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The COLA-vs-Real-Inflation Gap Nobody Talks About

Here's the problem: COLA is calculated using CPI-W, which tracks spending patterns of urban wage earners. Retirees aren't urban wage earners.

The BLS publishes CPI-E, an experimental index for Americans 62 and older (bls.gov/cpi, checked 2026-09-10), which over most of its history has run modestly higher than the CPI-W that actually sets the COLA (CWUR0000SA0). Why? Retirees spend more on healthcare and housing — the two categories with the highest sustained inflation.

A 3.6% COLA sounds generous until your Medicare Part B premium jumps 9.7% (up from $185.00 in 2025 to $202.90 in 2026, per the CMS 2026 fact sheet), your Medigap plan increases 8-12%, and your property taxes go up 4.5%. The net purchasing power gain from a "generous" COLA is often zero — or negative.

This is exactly why assuming a flat inflation rate in your retirement plan is dangerous. Your Social Security COLA might be 4%, your medical inflation might be 6%, and your housing costs might be 4.5%. A plan that models one number for everything misses the wedge that grows every year.

How This Affects Your Retirement Plan

If you're 5-10 years from retirement: The specific COLA estimate is noise. What matters is your assumed inflation rate during retirement. If your plan uses 2.5–3% uniform inflation and your actual medical costs inflate at 5-6%, your plan's success probability could be 10-15 percentage points too optimistic.

If you're already retired: At 3.6%, the 2027 COLA still trails the 9.7% Medicare Part B increase you just absorbed. The question is whether your overall withdrawal strategy accounts for this — or whether you're slowly losing purchasing power each year.

If you're planning Roth conversions: A higher COLA means higher IRMAA brackets in future years (they're inflation-indexed). Converting in a year when COLA pushes brackets up gives you slightly more MAGI room. But only if you're tracking the interaction between conversion income and Medicare surcharges.

If you're claiming Social Security soon: The timing calculus shifts. A higher COLA makes delayed claiming slightly more valuable — each year of delay now grows at the COLA rate on top of the 8% per year delayed retirement credit. If COLA averages 3.5% instead of 2.5%, the breakeven point for delayed claiming shortens by roughly 1-2 years.

What to Do About It

1. Don't plan with a single inflation number. Use category-specific rates: 3% general, 5-6% medical, 4% housing. This is closer to how retirees actually experience inflation.

2. Stress test the COLA gap. Run your plan twice: once assuming COLA keeps pace with expenses, once assuming a 1% annual shortfall. Over 25 years, a 1% COLA gap compounds to a 22% reduction in purchasing power from Social Security alone.

3. Check your safe withdrawal rate assumptions. The standard 4% rule was calibrated when inflation averaged 3.1%. If your real expenses inflate at 4-5%, your effective withdrawal rate is higher than you think.

4. Use Monte Carlo simulation to model the uncertainty. COLA won't be exactly 3.5% every year — it varies, and so does everything it's supposed to cover. A Monte Carlo retirement calculator runs thousands of scenarios with different inflation paths, so you see the full range of outcomes rather than a single guess.

QuantCalc models stochastic inflation by category — healthcare, housing, food, and general CPI each follow their own path with regime-switching between stable and volatile periods. This captures the COLA gap directly, showing you what happens when Social Security adjustments don't keep pace with retiree-specific costs. Try it free at quantcalc.app or upgrade to PRO for 10,000 simulations with full inflation modeling ($49 lifetime).

The Bottom Line

The 2027 COLA was announced on October 14, 2026: 3.6%, based on Q3 CPI-W data (SSA 2027 Cost-of-Living Adjustment (COLA) Fact Sheet). The 2027 COLA page shows how the formula produced it.

But the real takeaway isn't the number. It's the structural gap between COLA and actual retiree inflation that compounds every year. A good retirement plan doesn't just model average inflation — it models the categories that hit retirees hardest and stress tests what happens when the COLA doesn't keep up.

QuantCalc is an independent educational tool. Not affiliated with, endorsed by, or sponsored by the Social Security Administration or any referenced organization. Return assumptions derived from publicly available research. Not financial advice.