The SBT burdens of various industries during the sample period are indicated by their tax burden ratios, or the ratios of their total SBT Liabilities to their total Adjusted Tax Bases. These ratios are not true tax rates. The marginal tax rate is the portion of the next dollar earned (or dollar added in value) that is paid in tax; it is the true "effective" tax rate because it "effects" the decisions of the firm.

The term "effective tax rates" in the Treasury Report is misleading. The total tax liability divided by the total tax base could be called the average tax rate. The average tax rate, or tax burden ratio as it is called here, is a broad-based ratio that does not necessarily indicate the marginal rate prevailing at any one level of the tax base.

The tax burden ratio simply indicates the share of the value-added tax base consumed in Single Business Tax: a good measure of the tax burden. Table Three in section IV.A., Tables of SBT Data, lists the tax burden ratios for various industries during the sample period.