Correction: Earlier versions of this article about the possibility that plans for new office space in Tysons Corner could exceed a limit imposed by Fairfax County incorrectly referred to Elizabeth Baker as a land-use attorney for several of the landowners that have submitted projects. She is a land-use planner with Walsh Colucci Lubeley Emrich & Walsh PC, the Northern Virginia-based law firm that represents those landowners. This version has been corrected.

Plans to redevelop Tysons Corner limit total office space in the community to 45 million square feet through 2030, an amount that could be exceeded by companies that have filed plans for new projects.

Now Fairfax County is proposing to only count projects against the cap when they are further down the pipeline, a change developers say could hinder financing.

One year ago, county officials adopted a proposal to redevelop Tysons, its auto-centric jobs district, into a walkable downtown designed around four new Metro stations.

The plan put no limits on new housing in Tysons, a place where 100,000 people work but only 17,000 live. However, it capped office development.

County planners say this limit would allow them to monitor an office building’s impact on traffic.

But the limit also prompted developers to quickly file their projects with the county before the doors close on new office construction. Eight projects have been submitted as rezoning applications that must be approved by the county Board of Supervisors.

Most of these developments would replace Tysons’s car dealerships and aging storefronts with gleaming 20- and 30-story buildings. Many of them blend office, residential and retail space, and would be built in phases over many years. They include the expansion of headquarters for SAIC and Capital One.

About 27 million square feet of office space exist in Tysons, with plans for 6 million more already approved. That leaves room for about 12 million more square feet of office space under the cap set by Fairfax. But the proposed projects would add about 14 million square feet total. And the county expects two to three more projects that include office space to be submitted soon.

Increasing the development level would require approval from the Fairfax Board of Supervisors. So far, developers have submitted only conceptual plans, making it unclear to the county how new buildings will affect traffic.

Instead, county staff is recommending another solution: Count office space toward the development limit only when a builder submits a final development plan — the stage where a project has more detailed design and engineering. That way, the county would have a better idea of a building’s long-term traffic effects, said Walter L. Alcorn, who chairs a Tysons-focused panel of the county Planning Commission.

“The way these sites are ultimately designed will, in large part, drive how much automobile traffic is generated on the site, and frankly how much people” walk, bike or ride Metro to work, Alcorn said.

But the county’s suggestion adds a second step to the public approval process. After a project’s conceptual plans receive approval for a rezoning, its final development plan would have to return to the Board of Supervisors for review and a public hearing.

At that point, the county could modify transportation improvements included in the plan or make other changes. The uncertainty could affect financial planning, developers say.

“It places the developer in a very difficult situation to make commitments when there is some uncertainty about the development they’re going to get and the future cost of implementing that development,” said Elizabeth Baker, a land-use planner who works for a law firm that represents several of the landowners that have submitted projects.

Baker added that while one builder waits for additional county review, the development level of 45 million square feet could be reached by projects further along in the approval process.

One thing that developers and county officials both agree on is that it will take time before Tysons’s skyline sees several new high-rises.

“The market is not going to allow everything to be built at once,” Baker said. “It’s going to take years and maybe in the big [rezoning] cases, 20 years to build out.”

The Planning Commission’s Tysons Committee will resume its discussion about development levels at a public meeting Wednesday. The meeting will begin at 7 p.m. at the county government center, 12000 Government Center Pkwy., Fairfax.