Almost all cost-of-living raises are made annually. The Social Security COLA, for example, is based on the CPI-W measured from the third quarter of the prior year to the third quarter of the current year. The raise becomes effective in December and lasts for 12 months [source: Practical Money Skills].
When the Social Security program first began to pay benefits, it didn't include a cost-of-living raise. Raises were mandated periodically by Congress during the 1950s, 1960s and 1970s. The Social Security Amendment of 1972 required automatic COLAs beginning in 1975. But for these raises to engage, there had to be at least a 3 percent rise in the CPI-W from the previous year [source: Social Security Online/Cost of Living Adjustments].
Because inflation had tapered off, Congress eliminated the 3-percent "trigger" in 1986. Future raises in the Social Security COLA were linked directly to the CPI-W if it rose by more than 0.1 percent [source: Social Security Online/Cost of Living Adjustments].
Some employment contracts give annual raises that aren't tied to any index. For example, a union might negotiate a 3-percent wage hike for each year of a five-year contract. These raises are often referred to as cost-of-living raises but they differ from true COLAs. The amount of the raise is negotiated, not tied to the CPI. Workers receive the increase even if there's no inflation.
If you haven't received a raise in some time and inflation has eroded the buying power of your salary, you can consider asking your employer for a cost-of-living raise. You should be aware of the recent movement of the CPI. The BLS offers an online inflation calculator, which you can use to estimate your loss of buying power since your last raise. You can also cite industry statistics that show the level of wages in a particular area (the BLS Occupational Outlook Handbook is a good source). If you're transferred to a location with a higher cost of living, it makes sense to request a raise to offset the difference.
One thing to keep in mind is that cost-of-living raises aren't really raises. They're simply intended to keep your pay the same in relation to rising prices.
Read on for more information about cost of living raises.