Anticipated ticket prices for the new American National Theater were reported incorrectly in some of Thursday's editions. According to theater director Peter Sellars, tickets are expected to cost $15 and $20.

The Kennedy Center will announce today a major restructuring of its theatrical activities as the first step in the creation of the American National Theater there. The wide-ranging plans include lowering ticket prices, emphasizing noncommercial work and establishing a free experimental theater.

They signal the intention of the Center, which has long considered itself a national cultural resource, to create a theatrical institution on a plane with the National Theatre of Great Britain or the Comedie Francaise in France.

Like those institutions, the American National Theater will look to the dramatic heritage of the past and require significant subsidies to carry out its mission. But it will also collaborate with theaters across the country to develop a contemporary repertory.

"You should be able to come to the Kennedy Center and ask, 'What's going on today in theater in America?,' and then find out," according to Peter Sellars, the 27-year-old director and chief operating officer hired seven months ago by Kennedy Center chairman Roger Stevens and given "carte blanche" to shape the theater company.

Among the changes Sellars will announce:

* The American National Theater will operate on a year-round basis. The Eisenhower Theater, often a stopping-off place for commercial shows, will no longer be used as a "booking house for Broadway productions, but as a point of origin for serious work." Broadway musicals, however, will continue to play in the Opera House.

* Ticket prices for all plays will be changed to $20 and $15 (current prices generally range from $30 to $14.50). In addition, existing specially priced ticket policies will be maintained, so that senior citizens, the military and students will be able to attend plays for as little as $7.50.

* Beginning in May, the mid-sized Terrace Theater, located on the top floor of the Center, will become a home for productions imported from or developed with other theaters across the country.

* The Theater Lab, now only sporadically used, will be renamed the Free Theater and, also starting in May, will be opened without charge to the public. The facility, across from the Terrace Theater, will house experimental productions with "high visibility."

* Fifteen members of what will be a 20-member artistic board of advisers have been named. They include actor-director Orson Welles, entertainer Harry Belafonte, director Elia Kazan, performance artists Meredith Monk and Laurie Anderson, founder of La Mama Experimental Theater Club Ellen Stewart and other leading cultural figures.

* The Center's traditional subscription plan will be scrapped in favor of $75 and $100 memberships in the American National Theater, which will entitle holders to four or six passes, respectively, to any of the company's productions.

Today Sellars will also announce the first three plays scheduled for the Eisenhower: Shakespeare's "Henry IV, Part I," opening March 23; James O'Neill's adaptation of "The Count of Monte Cristo," May 11; and "Come on Over," a never-produced comedy about Washington by Mae West, June 29.