Budget is defined as A. control over the level of government spending. B. planned expected income and expenditure over a period of time. C. planned government expenditure of goods over a given period of time. D. money received from the tax revenue for planned expenditure.

The question asks for the definition of a budget.

• A. "control over the level of government spending." This describes a function of a budget, but not its definition.
• B. "planned expected income and expenditure over a period of time." This is the most accurate and comprehensive definition. A budget is a financial plan that estimates both revenues (income) and costs (expenditure) for a future period.
• C. "planned government expenditure of goods over a given period of time." This is too specific, focusing only on government expenditure and only on "goods," not services or income.
• D. "money received from the tax revenue for planned expenditure." This is also too specific, focusing only on tax revenue as income and not encompassing all aspects of a budget.

Therefore, the best definition is B.

The final answer is $\boxed{\text{B}}$