How FERS COLAs work: the diet-COLA rule
A FERS annuity is adjusted for inflation each year, but deliberately by less than inflation. When prices rise more than 2 percent, your pension rises by less. Most FERS retirees also receive no adjustment at all until age 62. Together these two rules shape your income for the rest of your life.
6 min read · By RetireCiv Editorial · Updated July 19, 2026
What is the FERS diet COLA?
The diet COLA is the nickname for a formula that pays you less than inflation on purpose. OPM applies three bands to the annual change in consumer prices, and only the lowest one gives you the full increase.
When prices rise 2 percent or less, you get the full amount. When they rise more than 2 percent but no more than 3, your adjustment is capped at exactly 2 percent. When they rise more than 3 percent, you get the increase minus a full percentage point.
The design has a clear consequence. In quiet years your pension roughly keeps pace, and in high-inflation years it visibly falls behind. Since the shortfall is never made up later, a run of inflationary years permanently lowers what your annuity buys.
CSRS retirees are not subject to any of this. They receive the full increase in every band, which is one of the more meaningful differences between the two systems.
The three COLA bands
| If consumer prices rise | Your FERS COLA is | A CSRS COLA would be |
|---|---|---|
| 2% or less | The full increase | The full increase |
| More than 2%, up to 3% | Exactly 2% | The full increase |
| More than 3% | The increase minus 1 point | The full increase |
What is the FERS diet COLA?
It is the rule that gives FERS retirees a smaller cost-of-living adjustment than inflation whenever prices rise more than 2 percent. If prices rise 2 percent or less you get the full amount. Between 2 and 3 percent, your adjustment is fixed at 2 percent. Above 3 percent, you get the increase minus one percentage point.
Why is my FERS COLA lower than inflation?
Because the formula is written that way. Congress set FERS COLAs below the full price increase in the two higher bands, partly because FERS retirees also receive Social Security, which is fully indexed. The reduction is permanent rather than deferred, so a year where you fall a point behind stays lost for the life of the annuity.
Do CSRS retirees get the same reduced COLA?
No. CSRS annuities receive the full price increase in every band, with no reduction at any level of inflation. That is why a long stretch of high inflation widens the gap between a CSRS and a FERS pension of the same starting size. If you have a CSRS component inside a transferred FERS benefit, that component follows the CSRS calculation.
Why do you get no COLA before 62?
Most FERS retirees receive no cost-of-living adjustment at all until age 62. If you retire at your MRA with 30 years, your pension can sit frozen in nominal terms for several years before the first increase ever arrives.
This is the part people underestimate. Retiring at 57 means roughly five years during which prices rise and your annuity does not move. The eventual COLA applies to that un-adjusted amount, so the purchasing power lost in those years is never restored.
Three groups are exempt and do receive adjustments before 62. Disability retirees, survivor annuitants, and special-provision retirees get them at any age. The public-safety exemption exists because those employees are required to leave early.
One narrow exception sits inside the disability rule. A FERS disability retiree does not receive the adjustment during the period they are being paid on the first-year 60 percent computation.
When do FERS COLAs start?
At age 62 for most retirees. If you retire earlier, your annuity generally receives no cost-of-living adjustment until you reach 62, no matter how many years that takes. Disability retirees, survivor annuitants, and special-provision retirees such as law enforcement officers and firefighters are exempt and receive adjustments at any age.
Does the Special Retirement Supplement get a COLA?
No. The Special Retirement Supplement is never adjusted for inflation. It is fixed at the amount calculated when you retire and stays there until it ends at 62. So an early retiree can spend years with both an un-adjusted pension and an un-adjusted supplement, which is the least inflation-protected stretch of a federal retirement.
Why do law enforcement retirees get COLAs before 62?
Because they have no choice about leaving early. Law enforcement officers, firefighters, and air traffic controllers face mandatory retirement well before 62, so applying the age gate would penalize them for a rule they cannot opt out of. Their annuities receive adjustments from the start of retirement.
How is your first COLA prorated?
Your first adjustment is almost never a full one. A full COLA requires having received payments for a full year, and anyone else gets one-twelfth of the increase for each month they were in receipt of benefits.
The arithmetic is simple once you see it. Retire three months before the adjustment takes effect and you receive three-twelfths of it. From the following year onward you are on the full amount.
This interacts with your retirement date in a small way, though it rarely deserves to drive the decision. Retiring a month earlier buys one more twelfth of one year's adjustment, which is real but modest next to the leave and salary effects of the same choice.
Two details round this out. Adjusted amounts are rounded down to the next whole dollar, and benefits paid to children are never prorated at all.
Why was my first COLA smaller than everyone else's?
Because it was prorated for a partial year. You receive one-twelfth of the adjustment for each month you were actually receiving payments before it took effect. Someone who retired nine months earlier gets nine-twelfths. From your second year forward you receive the full adjustment like every other annuitant.
Should I time my retirement date around the COLA?
It is a minor factor rather than a deciding one. Each earlier month adds one-twelfth of a single year's adjustment, which is small compared with what the same date change does to your final salary and your lump-sum leave payout. We lay out the mechanics rather than recommending a date; your leave balance usually matters more here.
What does the diet COLA cost over a long retirement?
The yearly shortfall looks trivial and compounds into something that is not. Falling one percentage point behind prices in a single high-inflation year is barely noticeable. Doing it repeatedly across a thirty-year retirement is not.
Suppose prices rise 5 percent in a given year. Your annuity rises 4 percent, so you have lost roughly a point of purchasing power that no future adjustment restores. The next year's COLA is applied to the smaller base, which is why the effect compounds rather than merely accumulating.
This is the strongest argument for treating your TSP as your inflation defense. Your pension is partly protected, Social Security is fully indexed, and the TSP is the piece whose growth you actually control.
To see how an under-indexed pension interacts with the rest of your income over a full retirement, run your free readiness score, and check our assumptions for the inflation figures behind the projections.
Does the FERS COLA keep up with inflation over time?
Not in higher-inflation years, and the gap is permanent. Because each shortfall lowers the base that future adjustments apply to, the losses compound across a long retirement rather than staying flat. Quiet inflation years cost you nothing, so the damage depends heavily on which economic conditions you happen to retire into.
What protects my retirement income from inflation?
Your three income sources are indexed very differently. Social Security tracks inflation fully. Your FERS pension tracks it partially, and only after 62. Your TSP has no automatic indexing at all, but its growth is the part you influence through how you invest and how much you withdraw. That contrast is why the TSP tends to carry the inflation-protection role.