There is a substantial difference in the number of taxpayers who might be impacted under two competing estate tax bills in the Senate, but analysts say taxpayers should not read too much into either since a final deal will not be negotiated for months. This week, the Senate will debate two very different proposals. A Republican plan (S. 3413) would extend for one year the current estate tax levels of a 35 percent tax and a $5.12 million exemption. A Democratic plan (S. 3412), however, does not address the estate tax at all. By excluding it from the bill, if not otherwise addressed, the maximum tax rate would revert to 55 percent while the exemption level would drop to $1 million.