Like other types of higher alcohol spirits, Soju doesn’t expire the same way that most foods does. However, its taste and quality may change over time if it is stored improperly or for an extended period of time. If Soju is stored in a cool, dark place and the bottle is sealed properly, it can last for several years. However, if the bottle is opened and the soju is exposed to air or light, it may begin to deteriorate and its flavor may change.
There’s enough alcohol in Soju (even the fruit Soju at about 13% abv) that you don’t have to finish an entire bottle in one serving. After it has been opened it is generally recommended to keep the bottle in the fridge where it can still last several months.
Most green bottle Sojus like Jinro, Chum Churum, or Good Day have a date printed on the front of the bottle. Many people mistake this date for an expiration date when it is, in fact, a manufactured date.
Soju is usually sold in small, single-serving bottles, which means that you may go through it relatively quickly. This means that you are less likely to have to worry about the Soju expiring, as it is easy to consume before expiring.
When a Soju is a higher proof like 41% or 53% it can last decades – particularly if it’s unopened and stored properly. If the bottles are opened they can still last for several years and maintain their original flavour and properties if the bottle has at least ~30% of the liquid remaining in the bottle. As with all spirits in that alcohol percentage range, if the bottles have less than 30% volume remaining the fumes can escape each time the bottle is opened and the structure/taste of the liquid can change.
As with all alcohols, it is also worth noting that the flavor and quality of Soju can be affected by how it is stored. If the bottle is stored in a warm, humid place or consistently exposed to light, it may develop off flavors or become less appealing to drink. To ensure that your Soju stays fresh and retains its original flavor, it is best to store it in a cool, dark place.
In general Soju will last a very long time and you don’t have to finish the bottle on the day that you open it. Store them in a cool dark place and try and keep them refrigerated after opening if the alcohol percentage is under 30%.