I can’t tell you how many times I’ve wanted to make something that requires buttermilk and I don’t have any on hand. Buttermilk just isn’t something I keep around regularly. This is a good trick to know and works as a great replacement for buttermilk. It works with both milk and soymilk. I have not tried it with almond milk but I think it would work the same (?).
Homemade Buttermilk
1 cup milk or soymilk
1 tbsp white vinegar
Stir vinegar into milk and allow to sit for several minutes to curdle and thicken. Use as directed in any recipe for buttermilk.
Everything Is Homemade 
yep I use it with almond milk all the time! I have never actually bought buttermilk, but I can tell a huge difference if I don’t make ‘buttermilk’ to use in my biscuits and just use plain almond milk.