I live in the US.. Can I upgrade to Home and Business from Home and Student?

I want to add Outlook to my Home and Student Office suite (for my Mac). I can't find any link that allows me to do just that.  I did read though, that upgrading is only available in some countries.  Truly MS wouldn't limit customers from upgrading their software.  Can someone point me in the right direction.  I did ask MS for help but all I got was a link to a page that doesn't allow me to upgrade.  Thank You.