firms. The association between size and tax rates is strongest in the oil
industry following the 1969 Tax Act and weaker, but statistically significant
associations are observed in manufacturing throughout the period 195&1981.
Moreover, tax rates do not increase monotonically with firm size. These
results are robust to (i) alternative measures of tax rates, (ii) alternative
sources of data, and (iii) different measures of firm size.
Three possible reasons for these results are examined: (i) fixed tax shields,
(ii) elimination of the oil depletion allowance, and (iii) foreign taxes. While
each of these reasons can explain some of the results, no single reason
explains all the results. For example, all three reasons are consistent with the
results in the oil industry, but the fixed tax shields and oil depletion
allowance explanations do not explain the findings in the manufacturing
industry. Data are not available to test the foreign tax explanation in the
manufacturing industry prior to 1970.