Families earning more than $1 million a year saw their federal tax rates drop more sharply than any group in the country as a result of President Bush's tax cuts, according to a new Congressional study. The study, by the nonpartisan Congressional Budget Office, also shows that tax rates for middle-income earners edged up in 2004 ... while rates for people at the very top continued to decline. While Mr. Bush's tax cuts reduced rates for people at every income level, they offered the biggest benefits by far to people at the very top - especially the top 1 percent of income earners. Two of his signature measures, tax cuts on investment income and a steady reduction of estate taxes, overwhelmingly benefit the wealthiest households. Households in the top 1 percent of earnings, which had an average income of $1.25 million, saw their effective individual tax rates drop to 19.6 percent in 2004 from 24.2 percent in 2000. The rate cut was twice as deep as for middle-income families. Those rates could decline even more as the estate tax on inherited wealth is gradually phased out by the start of 2010. Mr. Bush and his Republican allies in Congress want to permanently extend that tax cut and almost all of the others. The cost of doing that would be more than $1 trillion over the next decade. Families in the bottom 40 percent of income earners, those with incomes below $36,300, typically paid no federal income tax and received money back from the government.