Two former coworkers meet for lunch a few months after retiring. Marcus spent 34 years in CSRS and is drawing about $4,200 a month. Dana worked the same job for 30 years under FERS and draws about $2,700. She retired at 57 under the minimum retirement age with 30 years. Both open their January statements, and Marcus's pension went up. Dana's didn't. "Did they forget me?" she asks.

They didn't. This is how the two systems were built, and the gap is wider than most FERS employees realize until they're standing in it.

The CSRS rule: full inflation protection

CSRS retirees get a cost-of-living adjustment that matches inflation, as measured by the CPI-W. The calculation compares the average CPI-W for July through September against the same quarter a year earlier. The percentage change, rounded to the nearest tenth, becomes the COLA. It takes effect December 1 and shows up in January annuity payments.

There is no age threshold and no cap. If CPI-W rises 3.2%, a CSRS annuity rises 3.2%.

The FERS rule: a later start and a smaller raise

FERS has two built-in limits.

First, the age requirement. Most FERS retirees don't receive a COLA until the year they reach 62. A person who retires at 57 collects five years of a flat annuity, whatever inflation does.

Second, the "diet COLA" formula. Once eligible, the adjustment depends on how high inflation runs:

CPI-W increaseFERS COLA
2% or lessSame as CPI-W
Above 2% up to 3%2%
Above 3%CPI-W minus 1 percentage point

So in a year when CPI-W comes in at 8.7%, as it did for the 2023 adjustment, CSRS retirees got 8.7% and eligible FERS retirees got 7.7%. In a milder year at 2.5%, CSRS got 2.5% and FERS got 2.0%. The formula only matches full inflation when prices are rising slowly.

Who gets the FERS COLA before 62

The age rule has exceptions. COLAs generally begin right away for:

  • Disability retirees
  • Survivor annuitants
  • Law enforcement officers, firefighters, air traffic controllers, and certain other special-category employees who retired under their enhanced provisions

If you're in one of these groups, confirm your status with your agency's HR office or OPM, since eligibility details matter. If you aren't, plan on a flat check until 62.

What that gap costs in real dollars

Take Dana's case. Her FERS annuity is $2,700 a month, or $32,400 a year. Suppose inflation averages 3% over the five years until she turns 62. She won't see a raise in that time, so her pension's buying power shrinks by roughly 14%. In the old money, it feels like $27,950 a year, not $32,400. That's a hit of about $4,400 annually, and it never gets repaired. When her COLAs finally begin, they apply to a base that has already lost ground.

Marcus faces the same prices, but each year's increase is added to his base, so his annuity keeps pace. Over a 25-year retirement, that difference becomes very large.

This is not a flaw in how you computed your pension. It's a deliberate trade. FERS was designed as a three-legged stool of pension, Social Security, and TSP, and the pension leg was made smaller and less inflation-proof on the assumption that the other two would carry more weight.

Two details that trip people up

The first COLA is often prorated. If you retired recently, your first adjustment is usually reduced based on how many full months you were retired before the December 1 effective date. Someone who retired in July won't get a full-year raise. Later COLAs are full.

The FERS supplement doesn't get a COLA. If you retire before 62 and qualify for the special retirement supplement, which approximates the Social Security you earned during federal service, that payment is not adjusted for inflation. It also ends at 62. Many retirees mistake it for part of the basic annuity, but it follows different rules.

How this fits with Social Security and the TSP

Once a FERS retiree reaches 62 and starts Social Security, two COLAs come into play: the annuity COLA and the Social Security COLA. They are calculated by different formulas, so they can differ. Social Security passes through the full CPI-W change. In a year when inflation is 3.5%, a FERS retiree's Social Security might rise 3.5% while their pension rises 2.5%.

That's one reason the TSP deserves a deliberate inflation strategy. Unlike a pension, it has no automatic COLA. Your withdrawals are whatever you decide them to be, so the adjustment is up to you. A common approach is to set an initial withdrawal rate, then raise the dollar amount each year by inflation, while checking that the portfolio still supports it. The TSP's G Fund, which is Treasury-backed, and its stock funds behave very differently in high-inflation years, so mix matters.

For early FERS retirees, the TSP often covers the stretch between the supplement ending and the first COLA arriving. Some people draw a bit more in those years specifically to offset the flat pension. Others delay Social Security past 62 to lock in a higher inflation-adjusted base for later life. Neither is right for everyone. Both are worth modeling.

Taxes follow the COLA

A COLA raises your taxable income, because annuity payments are taxable except for the part that returns your own after-tax contributions. That portion is figured under the Simplified Method and stays fixed in the monthly amount. So when your gross pension climbs, the taxable piece climbs by the full raise. Adjust your federal withholding using a Form W-4P through OPM if you notice a gap at tax time, and check irs.gov for current brackets and thresholds. They shift every year.

Practical steps

  • Look up the current COLA. OPM publishes the new percentages each fall after the CPI-W release. Percentages and thresholds change annually, so use the current-year figures, not a remembered number.
  • Build a year-by-year income plan that shows when each source starts: annuity, supplement, Social Security, and TSP withdrawals. Mark the age-62 transition.
  • Stress test for higher inflation. A 4% year is far more painful for FERS than for CSRS, so run that scenario.
  • Review your TSP allocation and withdrawal approach at tsp.gov, which has calculators and current rules for withdrawals.

Dana's January statement was right, and so was Marcus's. They simply live under different rules. Knowing yours before you retire gives you time to plan for the difference, rather than discovering it over lunch.