Quick answer
Use a neutral or natural expression for U.S. passport and visa photos. Keep your mouth closed, eyes open, and face relaxed. A slight closed-mouth expression may be acceptable, but a broad smile, open mouth, squint, or head tilt can make the photo risky.
The point is not to look severe. The point is to keep facial landmarks in a normal, easy-to-verify position.
Why expression matters
Biometric review depends on consistent facial landmarks: eyes, nose, mouth, jaw, and the relationship between them. A big smile changes cheek shape, narrows the eyes, raises the mouth corners, and can expose teeth. That might be a great personal photo. It is less useful as a document photo.
In practice, this usually fails when people copy social-photo habits. They smile, tilt the head a little, and lift the chin because it looks friendlier. The final image becomes less neutral and sometimes less symmetrical. Passport and visa systems reward boring consistency.
Most teams miss this part in photo validation: expression and head angle often change together. A smile is rarely just a smile; it often brings squinting, chin movement, or shoulder tension.
Closed mouth and relaxed face
A closed mouth is the safest choice. Keep the lips together naturally, avoid pressing them tightly, and relax the jaw. The expression should look current and human, not forced. Think "resting attention" rather than "serious face." That small adjustment makes the photo look less stiff without crossing into a smile that changes the face.
If the applicant has trouble relaxing, take several frames. The first shot is often awkward. A short pause, a normal breath, and a second attempt usually produce a better neutral expression.
The key takeaway is that neutral does not mean angry. It means stable, clear, and easy to compare with the person in front of the reviewer.
Eyes, head angle, and camera position
Both eyes should be open and visible. Avoid squinting, blinking, or looking slightly away from the camera. The head should be straight, with the camera at eye level. Looking up or down changes the face shape and can make the crop feel wrong even when the file dimensions are correct.
Light affects expression too. Bright direct light makes people squint. Overhead light creates dark eye sockets that can look like closed or shadowed eyes. Use soft front light and take the photo when the person is comfortable.
This looks good on paper, but it is one of the easiest problems to miss on a phone screen. Zoom into the eyes before exporting.
Children and infants
Rules are more flexible for babies and very young children because perfect expression control is unrealistic. Still, the face should be clear, the child should be alone in the photo, and the image should avoid obvious obstruction. For older children, aim for the same neutral or natural expression used for adults.
Do not use a toy, hand, or parent support in the final frame to force a smile or eye contact. It is better to take many attempts and choose the clearest acceptable image. Baby photos are often a numbers game.
A common pattern across experienced workflows is patience over editing. Wait for a usable moment. Do not manufacture one with software.
When to retake
Retake when the mouth is open, teeth are strongly visible, one eye is closed, the head is tilted, the person is laughing, or the expression clearly changes the shape of the face. Do not try to edit the mouth or eyes into compliance. Those are identity features.
If the only issue is crop or file size, fix the export. If the expression itself is the issue, retake. That distinction keeps the workflow clean and avoids risky edits.
If you simplify it, choose the frame where the person looks most like they would at an identity check.