Analysis also was carried out to ascertain the changes in philanthropic behavior
due to the change from the deduction system to the tax credit system. The
implications from the above is that the tax cost of giving does not appear to be an
element in the decision whether or how much to give to charity. However, the
crossing of the threshold of the superdeduction may well play an important role.
Those taxpayers with lower marginal tax rates in the three years had mixed results.
Taxpayers in the middle quintiles (covering deciles 3–6) showed a decrease in the
percentage giving over $250, whereas taxpayers in the top quintile (deciles 9 and
10) showed increases. The results for taxpayers who were in the highest marginal
tax rates in the three years were consistent. A greater percentage of these taxpayers
(other than those taxpayers in the first quintile) gave more than $250 in 1988 and
1992 than in 1986. This indicates that the threshold for the increased tax credit is
more important to higher marginal tax rate taxpayers than to lower marginal tax
rate taxpayers.