Apple first launched the battery replacement program in August of 2014.
Apple has determined that a very small percentage of iPhone 5 devices may suddenly experience shorter battery life or need to be charged more frequently. The affected iPhone 5 devices were sold between September 2012 and January 2013 and fall within a limited serial number range.
Initially, Apple said that the program would cover iPhone 5 batteries for "two years after the first retail sale of the unit or until March 1, 2015."
However, the program has now been extended to cover "affected iPhone 5 batteries for 3 years after the first retail sale of the unit." That means that depending on your device, it qualifies for a battery replacement until September 2015 or January 2016, at the latest.
You can check your serial number and get more information about how to replace your battery at the link below.
Read More [via Gabriel]