What it is:
A tax base is the total amount of assets or revenue that a government can tax.
How it works (Example):
For example, let's assume that in Big Town there is $500,000,000 of commercial and residential real estate that is subject to property taxes. If the local school district gets all of its funding from those property taxes, then its tax base is $500,000,000.
Taxes can be based on any kind of asset or revenue stream. For example, to calculate the tax base for a sales tax, you may consider the total spending power of the adults in the community as the tax base. Revenue streams from a gas tax might consider total gas station revenue as the tax base.
Why it Matters:
The size and growth (or lack of growth) of the tax base is crucial to the planning efforts of any local, state, or federal government. Because the size of the tax base influences the taxable revenues that are available to a government, there is a direct correlation between the economic condition of a city as a whole and the budget of the government that serves it. Accordingly, governments must always consider how their decisions will affect their tax base.