Why might somebody use a Goldman Sachs Tax-Smart Bonds Portfolio?

The Goldman Sachs Tax-Smart Bonds portfolio aims to give high-income investors a potentially lower-risk investing portfolio that is designed to potentially increase after-tax yield. The portfolio is dynamic, meaning Betterment personalizes it to the tax information you give us in your financial profile. 

Betterment offers a few bond and cash portfolio options. When you create a bond investing account, Betterment will provide personalized after-tax yield information to help you compare these options and allow you to choose the best portfolio for your goals and financial situation.