Jennifer Blouin (Penn, Wharton School), Jana Smith Raedy (North Carolina, Kenan-Flagler Business School) & Douglas Shackleford (North Carolina, Kenan-Flagler Business School) have posted Did Dividends Increase Immediately After the 2003 Reduction in Tax Rates? on SSRN. Here is the abstract:

The Jobs and Growth Tax Relief Reconciliation Act of 2003 reduces the maximum statutory personal tax rate on dividends from 38.1% to 15%. This study analyzes dividend declarations in the quarter following passage. Aggregate dividends rose by 9% when boards of directors first met following enactment. Consistent with the dividend changes being tax-motivated, they are increasing in the percentage of the firm held by individuals. Dividend changes also increased with insider ownership, consistent with managers acting in their own interests. However, these results are limited primarily to firms that made large, special dividends. We find little evidence of an increase in regular, quarterly dividend payments