In the UK, a passport photo must be signed (countersigned) by a person known as a countersignatory to verify the applicant's identity. This person must have known the applicant for at least two years, hold a current British or Irish passport, live in the UK, be from an accepted profession, and cannot be related to, live with, or be in a relationship with the applicant. Some acceptable professions include medical professionals (excluding doctors), lawyers, accountants, civil servants, teachers, post office officials, nurses, and engineers. The countersignatory must sign the back of one passport photo with a specific statement confirming the photo is a true likeness of the applicant, along with their signature, printed name in block capitals, professional or employer details, and how long they have known the applicant.
For online applications with a digital photo, someone can confirm the applicant's identity online without needing to sign a printed photo. The applicant provides the name and email of the person confirming identity, who then completes the confirmation process online.
The countersignatory must be someone of good standing in the community or a recognized profession and must be able to identify the applicant personally, such as a friend, neighbour, or colleague, but not just a professional acquaintance.
This countersigning requirement applies for first adult and child passports, replacements for lost or damaged passports, renewals for children under 11, or when an adult's appearance has significantly changed.