There is no expiration date on the storage of an incandescent light bulb. As long as it is kept dry, it can be stored for many years and still work properly when screwed into a socket.
Once the bulb is in use it does have an expected life span which varies according to the manufacturer and the bulb's wattage.
Incandescent Bulb Banned
In 2007, Congress passed a billed which outlaws the incandescent light bulb by the year 2014. All incandescent bulbs will be gradually phased out beginning with the ones of greater wattage.
By 2014, all incandescent bulbs are expected to be phased out.
Use Them Now
Most incandescent bulbs have an expected life span of approximately six months, depending upon several factors. Since the incandescent bulb has been banned and is no longer being manufactured in America, it would be wise to go ahead and use your incandescent bulbs before 2014.
After that, there may be fines or penalties of some sort for those who get caught using incandescent bulbs.