Final answer:
The surplus value of taxes used for social services relates to the concept of social benefits, there is no specific term for it. This surplus may contribute to a social rate of return by funding services beneficial to society.
Step-by-step explanation:
The surplus value of your taxes that are used for social services does not have a specific term, but it is closely related to the concept of social benefits. These social benefits include private benefits and external benefits that accrue to society from government spending, which can be funded through surplus tax revenue. When the government collects more in taxes than it spends, this creates a budget surplus. This surplus can be allocated to different uses, including social services, which are intended to generate a social rate of return by providing benefits to society as a whole, such as free education or Social Security.