Budget Surplus

Budget surplus is a term usually used in reference to govermental bodies. An individual, on the other hand, would likely refer to their savings (although you could say you have a budget surplus this month, if the term really strikes your fancy).

This budget surplus occurs when the income outpaces the expenses. For a governmental agency, this could be spent on repairs, debt, hush money, etc. A budget deficit is the opposite: the expenses are more than the income, and so there is a lack, usually covered by borrowed money.