N.H. Rev. Stat. Ann. § 230-A:7

After the highway planning corridor return has been filed, no person shall subdivide any land, begin any development, or alter or expand any structure or use of land within such corridor, without first obtaining a corridor permit from the layout authority or its designated agent. The layout authority shall adopt by rules pursuant to RSA 541-A the form for corridor permits, and what constitutes submission of a completed application. No existing structure or established use of property within the corridor shall be affected.