Assume that the government increases spending by $200 billion at the start of each year and maintains this policy for the next three years from now. Economists estimate the spending multiplier to be 2 and the impact is exhausted within each year (all induced consumption is completed within 12 months). The tax multiplier is estimated to be equal to 1 and the current average tax rate is equal to 25 per cent (so tax revenue rises by 25 cents for every extra dollar of GDP produced ). What is the cumulative impact of this fiscal expansion on GDP after three years?
Answer: $1200
The answer is $1200 billion.
In Year 1, government spending rises by $200 billion, which leads to a total increase in GDP of $400 billion via the spending multiplier. The multiplier process is explained in the following way. Government spending, say, on some equipment or construction, leads to firms in those areas responding by increasing real output. In doing so they pay out extra wages and other payments which then provide the workers (consumers) with extra disposable income (once taxes are paid).
Higher consumption is thus induced by the initial injection of government spending. Some of the higher income is saved and some is lost to the local economy via import spending. So when the workers spend their higher wages (which for some might be the difference between no wage as an unemployed person and a positive wage), broadly throughout the economy, this stimulates further induced spending and so on, with each successive round of spending being smaller than the last because of the leakages to taxation, saving and imports.
Eventually, the process exhausts and the total rise in GDP is the "multiplied" effect of the initial government injection. In this question we adopt the simplifying (and unrealistic) assumption that all induced effects are exhausted within the same year. In reality, multiplier effects of a given injection usually are estimated to go beyond 4 quarters.
So this process goes on for 3 years so the $600 billion cumulative injection leads to a cumulative increase in GDP of $1200 billion.
It is true that total tax revenue rises by $300 billion but this is just an automatic stabiliser effect. There was no change in the tax structure (that is, tax rates) posited in the question.
That means that the tax multiplier, whatever value it might have been, is irrelevant to this example.
Some might have decided to subtract the $300 billion from the $1200 billion to get answer (d) on the presumption that there was a tax effect. But the automatic stabiliser effect of the tax system is already built into the expenditure multiplier.
Some might have just computed $300 billion and said (c). Clearly, not correct.
Some might have thought it was a total injection of $200 billion and multiplied that by 2 to get answer (b). Also, not correct.
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