The balanced budget multiplier refers to the economic concept that a change in government spending, paired with an equal change in taxes, will lead to a proportionate increase in overall economic output. This means that when the government increases its spending while simultaneously increasing taxes by the same amount, the economy experiences a boost due to the additional income generated by the spending, which leads to increased consumption and investment. The balanced budget multiplier is typically equal to one, indicating that the increase in output is equal to the amount of new spending.