Effective April 2, 2018, the cost to execute a U.S. passport using the DS-11 form (first-time applicants over age 16; children under age 16; applicants re-applying after reporting a previous passport lost or stolen) will increase from $25 to $35.
Passport execution involves the submission of a passport application in person to a passport acceptance agent for identity verification and document review. The majority of passport applications are executed before a U.S. Postal Service passport acceptance agent, and many are executed before state and local government officials as well. Approximately 10 percent of in-person passport applications are executed before a Department of State official.
The Department of State generally sets consular fees at an amount calculated to achieve recovery of the costs to the U.S. government of providing the consular service. The Department last adjusted the passport execution fee in February 2008.
More detailed fee information can be found at https://travel.state.gov/content/travel/en/News/passports/execution-fee-increases.html (the Bureau of Consular Affairs website) and on the U.S. Embassy Sofia website.