Could not tell you one way or the other to be truthful, but, why chance it. My API Master Kit which I bought a year ago has an October 2021 expiration date; I will have used it up and replaced all of the chemicals long before that. In fact, I bought a new ammonia and nitrite kit recently as I used the ones in the kit up cycling several tanks.fishinagain said:They come with an expiration date. Is that a hard date or is it like a lot of other things? A date to make us let go of money to buy more creating waste?