A money market like mentioned, or a laddered CD system. Take 1/12 or 1/6 of your safety money and put it into a 12-month or 6-month CD. Repeat each month so that in the end you will have all of that safety net money in 12, 12-month or 6, 6-month CDs. This gives you a CD maturing each month which keeps it semi-liquid, and also you can simply allow the CD to renew if you do not need that extra money at that time.