Among the business put aside by the Senate as it's been focused on healthcare reform is the national inheritance tax on dead people's estates, which will otherwise expire for a year on Jan. 1 - and then return, bigger and broader, in 2011.

A Bush-era law temporarily repeals the tax, which currently clips 45 percent of everything you're left above $3.5 million, for all of 2010. That makes next year a convenient time for Uncle Moneybags to die.

But without a new tax law, the tax is scheduled to return in 2011, at around 55 percent - after the first $1 million.

If nothing's done, total estate (and related gift) tax revenues for Uncle Sam will slip from around $22 billion this year, to around $15 billion next year - then jump to $35 billion in 2012, as more estates are subject to the tax under the scheduled lower limit, the Congressional Budget Office estimates.

House Bill 4154, passed with Obama's support, would extend the estate tax more or less on today's terms. That would keep next year's estate-tax receipts around this year's level, while also limiting the scheduled increases after that, according to CBO.

"Let's say your parents have a little Shore house," says Marguerite Mount, principal with Hamilton Township-based tax advisors Mercadien PC. "They paid $200,000 for that Shore house. They die, and you inherit that Shore house in 2010, and it's worth $2 million." Which is below the old estate tax minimum. Nice.

"Now let's say you want to sell it. Under 2009 rules, you don't have to pay inheritance tax," since the house is worth less than the $3.5 million limit.

But under 2010 rules, without that inheritance-tax protection, "you'll have to pay capital gains tax" of around $360,000 on the $1.8 million gain in the house's value over the years, compared to what your parents paid way back.

Add the impact on a main residence, insurance policies, retirement accounts, and this gets complicated quick. "We can't help people plan if we don't know where this is going," Mount said sweetly. "If they go with the $1 million (inheritance tax minimum) in the current law, we'll have, I don't know, ten times as many people paying inheritance taxes. And if they don't pass the changes until well into next year, we could be facing a retroactive tax."

Sounds like plenty of work for tax accountants, either way.