I use this account for my emergency cash fund, and keep 6 months expenses in it at all times. Currently very low yielding (If you keep less than 10k in it, it earns the same interest as their interest bearing checking accounts.) It does allow me to keep my accounts separate though so I am not tempted to spend the money. It offers tiered rates, but even large balances receive very low yields. I would recommend you use this as a rainy day fund so you don't have to dip into investments or retirement accounts if something unexpected comes up, but it isn't a very useful tool if your goal is to earn money.