"There are probably many influences on Buffett to give the money over a series of years rather than all at one time, I am sure that one of them is the tax ramifications. Charitable gifts of appreciated stock such as his Berkshire shares can only be deducted when given to a public foundation to the extent of 30 percent of your income. Any amounts over and above the 30 percent are carried forward for five years.
Although I don't know what Buffett's adjusted gross income is, my guess is that the $1.5 billion will probably fit somewhere into that limitation. The Gates Foundation will continue to receive the gifts either directly from Buffett or through his estate, as long as Bill or Melinda Gates are active in the foundation. Here again, this will afford the Buffett estate a deduction for gifts after his death since they go to a charitable foundation.
Based on recent Internal Revenue Service statistics, estates that had over $20 million of taxable assets saw charitable giving actually fall by an average of $2 million or 9 percent from 1995 to 2004. Buffett has gone a long way in reversing this trend. Perhaps other charitable minded individuals will reconsider their charitable bequests. Even if you are not in the multi-million dollar category, there are many ways that you can take advantage of the gifts that you do make during your life or bequests on death."