The head of the nation’s largest umbrella group for nonprofits urged reinstatement of the estate tax to 2009 levels to encourage charitable giving.

“Permanent repeal of the estate tax could result in the loss of $1 trillion in tax revenue over 10 years,” said Diana Aviv, president and CEO of Independent Sector, a Washington-based organization composed of nonprofit groups, foundations and corporate-giving programs.

Aviv spoke Monday to about 100 leaders of the region’s nonprofit community at a seminar sponsored by Grantmakers of Western Pennsylvania in the August Wilson Center for African American Culture, Downtown.

The estate tax expired at the end of 2009 and is scheduled to return Jan. 1, with a $1 million exemption and the balance of the estate taxed at 55 percent.

Some senators, however, are trying to reinstate the estate tax sooner under terms that Independent Sector believes could hurt charities.

Aviv favors the reinstatement of the 2009 terms, which are supported by the House and President Obama. Last year, the first $3.5 million of an individual’s estate, or $7 million for a couple, was exempt, and the balance was taxed at 45 percent.

Aviv urged support of the Nonprofit Sector and Community Solutions Act of 2010, proposed by Rep. Betty McCollum, a Democrat from Minnesota.

The bill would create a 16-member council to strengthen the links among Congress, the White House and the nonprofit community. It would create an interagency working group consisting of cabinet members and directors of relevant agencies, and would require the federal government to collect data on nonprofits.

“I don’t think anybody thinks it will be passed this year,” Aviv said. “The hope is that the next two or three years will build enough support to get it passed.”

Aviv contends that nonprofits deserve a seat at the table in Washington. Some 13 million people work full time for nonprofits, or 10 percent of America’s work force.

“I like the idea that the federal government, in addition to mandating regulations, might help the nonprofit sector do what it does better,” said Gregg Behr, executive director of The Grable Foundation, a Downtown philanthropy.