The reported size of the National Trust for Historic Preservation's budget was incorrect in Saturday's editions. It is $21 million.

The National Trust for Historic Preservation announced a major reorganization this week aimed at making the congressionally chartered preservation group a more aggressive lobbyist and leader in state and local land use and urban renewal debates throughout the United States.

The reorganization, which includes five new vice presidents chosen from outside of the nonprofit preservation community, effectively centralizes in Washington a number of functions of the group's six regional offices, such as fund-raising and some program activities.

"Up till now the preservation movement has been a series of relatively random efforts to save specific buildings," said trust President J. Jackson Walter. "We want to go beyond that now, be a major central figure in public debates about what our cities should look like, where tall building should go, and try to put historic preservation right in the middle of those debates instead of at the end."

While the reorganization has been greeted with cautious optimism by many preservationists, others have criticized the shuffle, saying it will take away local authority and deprive the network of small preservation groups of the national organization's support. That backing traditionally has been funneled through the regional offices of the trust.

Some have questioned the trust's wisdom in cutting back the regional operations, saying that it is important that the trust have strong offices at the local level if it is serious about getting involved in local land-use policy issues.

"Our biggest concern is that the trust should decentralize, give more resources to its regional offices," said one preservationist who requested anonymity. "This effort does exactly the opposite. One of the real challenges facing the trust is that the partnership between preservationists and investors and developers be strengthened at all levels. We'll be watching to see if that happens under this reorganization."

Walter, however, said the changes are necessary if the trust is to push beyond its traditional boundaries and become an active participant in local decisions about development and urban renewal in general.

"The most inventive and the most powerful city-shaping device the government has come up with in years and years is the historic rehab tax credit," Walter said. "The power of the tax act suggests that the role of preservation is now recognized at the local level by mayors, developers and investors. We need to carry that forward."

The preservation community pulled together an unusual coalition of supporters this summer in its effort to retain the historic rehabilitation investment tax credits, slated to be killed as part of the Reagan administration's tax reform proposal.

The tax credits, which have been in effect for three years, allow developers a tax credit of 25 percent of their rehabilitation costs for a qualified historic rehab if it meets certain design criteria. Owners of rehabilitated buildings that are 40 or 30 years old are allowed a tax credit of 20 or 15 percent, respectively, and are not required to meet specific design standards. The tax credits are allowed only for commercial properties.

The trust estimates the tax credits have stimulated $5 billion worth of rehab investment work on 6,800 buildings across the country in the past three years. A new national industry of historic rehab developers and tax syndicators, now strong advocates for the tax credits, have sprung up as historic tax credit building has increased.

While the fate of the tax credits is difficult to predict, Walter said he is "optimistic" that the preservation community has a good chance of surviving any tax changes.

The trust itself, however, has seen a gradual erosion of its federal support over the past eight years. Chartered in 1949 to encourage public participation in the preservation of historic sites, the trust receives only 20 percent of its $2.24 million annual budget from the federal government, down from 50 percent in 1976. Each year since 1981 the Reagan administration has proposed cutting out the trust's support completely.

Congress has restored its funding each year, but cautioned the trust last year that it should start searching for more private support.

"We need to pay our own way," said Walter. "While we've done a pretty good job, we need to do that better if we are going to grow and expand our programs."

One of the five new vice presidents announced this week is fund-raiser David R. Jones, vice chancellor for development at Vanderbilt University. The others are Sally G. Oldham, executive vice president for Langelier Historic Properties, a company specializing in syndications of historic rehab tax credit projects; Frank Emile Sanchis III, an architect and executive director of the Landmarks Preservation Commission of New York City, and Marcia Myers, acting environmental director for the city of Boston.

Walter said that Oldham will oversee the trust's grant and loan programs, including the popular Main Street revitalization program; Sanchis will handle the trust's historic properties and Myers will oversee a new maritime preservation department that will coordinate waterfront development and preservation efforts. Walter also has named a fifth vice president who will be the trust's general counsel, but has not identified the appointee as yet.