The widow is not the only client of Roeser's concerned about her legacy. The $5 million exemption on estate taxes and lifetime gifts, law since 2009, is due to evaporate on Dec. 31, keeping tax lawyers and financial planners across the country busy.

With Congress and the White House focusing on talks about changes to the income and capital gains tax rates, relatively little has been said about the largest tax bump on the horizon: Without a consensus in Congress, the tax rate on estates and lifetime gifts will rise from 35 to 55 percent. That 20 point jump makes the potential rise in top income tax rates, from 35 percent to a threatened 39 percent, look like small potatoes.

More dramatic yet is the amount of money exposed to the tax: The current tax rates apply only to estates of more than $5 million. The end of the Bush tax cuts would reduce this exemption to $1 million. (Read More: American's Grades for Personal Finance Are Up — Barely)

Returning to a $1 million ceiling will mean the estate tax will touch many more people than it did when the Bush tax cuts were passed a decade ago. "An average American can have 1 or 2, or even 3 million dollars and not be wealthy," Roeser said.

Which is why Roeser and other financial planners believe that the estate tax and the lifetime gift exemption will be reset to a figure somewhere around $3 million — if for no less cynical reason than that's what the average congressmember is likely to have in investable assets.

That's still a lot of cash that the taxman can't touch, especially considering that, since spouses can each give away an amount up to the exemption without incurring taxes, the exemption for a married couple would be $6 million.

So before writing big Christmas checks to the kids, financial planners say, consider whether you really have enough money to worry about beating the "fiscal cliff" deadline. (Read More: 'Rare Good News' on Retirement Savings)

"It's a relatively small group of people who really need to worry now," said Michael S. Beriss, a former tax attorney who is now a financial planner with Ameriprise. To take full advantage of the current $5 million exemption, a married couple would have to have a spare $10 million in the bank. "If you give away $1 million today, you're not using your $5 million exemption," he said.

If you are ready to part with that kind of gift, planners say, by all means take advantage of a deal that's probably not going to get better. But not everyone has enough, or is old enough, to part with that much of their holdings, as Roeser reminded her widowed client. "I told her, 'You're 70 years old,'" said Roeser. "You don't know yet what your health-care costs are going to be.'"

That doesn't mean an older investor with investable assets and a home worth more than $3 million should do nothing, financial planners say. But it's not time to panic. Instead, it's time to do some planning.

For financial advisers, it should be noted, planning rarely seems to mean plotting how to sequester funds so the government can't get to it. "You may have other objectives than keeping your taxes down," said Beriss. "The real question you need to start with is: What are you trying to accomplish? What legacy do you want to leave?"

The legacy you envision should determine what kind of tax relief you choose. If you want to send your grandchildren to college, a 529 college savings account makes the most sense; if you want to support a cause, a charitable contribution may be the best way to protect your money. Trusts may be the smartest answer if your main objective is to make your kids' lives easier financially without leaving them with tax headaches themselves.