Herndon officials have come up with a new twist to a proposed controversial land swap between the Northern Virginia community and Fairfax County.

The proposal, which has been stalled in negotiations with town and county officials for two months, would exchange 100 acres of undeveloped commercial property in Fairfax County for almost 72 acres of residential and commercially zoned property in Herndon. The agreement also requires Herndon to relinquish its right to apply for city status for at least 25 years, a condition that residents and Town Council members have refused to accept.

But late last week, council members said the town would go ahead with the land exchange if the county agrees to nullify the swap in the event that Herndon applies for city status.

"If the town went city, then the lands exhanged would revert back to their original jurisdictions," Vice Mayor Pamela S. Tennyson said.

Mayor Richard C. Thoesen said he will meet with district Supervisor Nancy K. Falck (R-Dranesville) to discuss the town's counterproposal. "I want to see if she'll carry the flag for the town and convince the other supervisors on our behalf" to approve the proposed alternative, Thoesen said.

Falck, who favored the initial land exchange idea, said earlier that the county should get a greater return on the swap than just the two parcels of land inside Herndon's boundaries. But Thoesen said that taking away the town's right to apply for city status was a "loss of political face and town pride" for the community of 14,000.

"People in Herndon expect a fair shake from the county, and the county expects a fair shake from Herndon. What we're giving the supervisors now is a fair alternative," Thoesen said in a telephone interview.

Council member Robert P. Jensen said Herndon's proposal is designed to meet the needs of both the county and the town. "Our counterproposal gives us some control over the building of our border, and it gives the county what it was looking for in the protection of their tax income."

Council members estimated that with the land exchange, the town could reap $375,000 a year by 1991 in added tax revenue from potential commercial development on the site.

Falck said earlier that the 25-year stipulation was the county's guarantee against possible land revenue losses if the town ever attained city status. "If Herndon decides to become a city . . . , the county loses a substantial amount of revenue," she said.

Town residents and businesses now pay county taxes as well as Herndon taxes. Should Herndon become a city, all local revenue would go to Herndon.

The land swap involves 58 acres of undeveloped residential property along Stuart Road that is owned by Reston Land Corp. and 14 acres of commercial property south of the Dulles Toll Road that is owned by GTE Corp. Batman Corp. owns seven acres of the 100-acre tract in the county, and Worldgate Office Park Inc. owns the other 93 acres there.

In April, the Town Council voted 4 to 3 to renegotiate the terms of the boundary exchange with county officials. Thoesen said he would hold more public hearings on the latest land proposal by September.