Lagged COLA Calculator
Apply inflation from an earlier reference period.
Lagged COLA Calculator: Scenario Inputs
Annual percentage rate or benchmark index change.
Inflation & Purchasing Power Analysis
Over 3 years at 3.5% inflation, a $75,000 salary requires $83,154 to retain equal purchasing power. Without matching raises, your real compensation experiences an effective reduction of $7,355 (-9.81%).
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How Lagged COLA Calculator Works?
The Lagged COLA Calculator works by applying each year's adjustment from inflation measured in the earlier period.
Enter pay
Type the pay or benefit before the first lagged COLA.
Set the lag
Choose the lag length, such as 1 year or 1 quarter.
Enter inflation
Type inflation for each period in date order.
Read the lag cost
The output shows lagged pay, same-period indexed pay and the gap each period.
Lagged COLA Calculator Formula
The Lagged COLA formula sets this period's COLA equal to inflation from the earlier reference period.
COLAt = πt−L
Gapt = Pay0 × [Πk≤t(1 + πk) − Πk≤t−L(1 + πk)]
Variables
- L
- Lag in periods
- πt−L
- Inflation in the reference period
Worked example
With a 1-year lag, the 8.0% inflation of year 3 reaches pay in year 4. During year 3, a $50,000 benefit stands at $52,978 against prices that call for $57,216, a gap of $4,238.
Lagged COLA Calculator Conversion Table
This table compares a 1-year lagged COLA with same-year indexation for a $50,000 benefit.
| Year | Inflation that year | COLA paid (prior-year inflation) | Lagged pay | Same-year indexed pay | Gap |
|---|---|---|---|---|---|
| Year 1 | 1.2% | — | $50,000 | $50,600 | $600 |
| Year 2 | 4.7% | 1.2% | $50,600 | $52,978 | $2,378 |
| Year 3 | 8.0% | 4.7% | $52,978 | $57,216 | $4,238 |
| Year 4 | 4.1% | 8.0% | $57,216 | $59,562 | $2,346 |
| Year 5 | 2.9% | 4.1% | $59,562 | $61,290 | $1,727 |
What is Lagged COLA Calculator?
The Lagged COLA Calculator is a tool that applies a cost-of-living adjustment (COLA) based on inflation from an earlier reference period, such as the prior year. Most COLAs are lagged, since the inflation data has to be published before the adjustment is set.
A lag means pay trails prices during rising inflation and catches up 1 period later.
What are the uses of Lagged COLA Calculator?
There are 4 main uses of the Lagged COLA Calculator.
Explain COLA timing
Show why COLAs trail price rises.
Cost the lag
Measure what recipients lose while waiting for the adjustment.
Compare lag lengths
Compare 1-quarter and 1-year lags.
Support interim payments
Size an interim payment during fast inflation.
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