The year it was made is on the colored paper in the box under batch. It has about a 2 year shelf life. Below is from a old post of mine.

Quote Originally Posted by jeffman
If the last two numbers end in 03 through 05, Spectrum labs will trade it. QF 4.0, ending in 06,07,08 are good and 4.2 ends in 08 and 5.7 should end in 09 I would think.