Start with the moment of submission. What will the form ask you to upload or hand over, and what exact checks can fail? Work backwards from those answers.
Work from hard limits to soft judgments
File size and dimensions can usually be checked numerically. Face position, lighting and background need a visual review against the official examples.
Keep a copy of the version that failed
When troubleshooting, do not overwrite the previous file immediately. A simple filename such as passport-original.jpg, passport-size-fixed.jpg and passport-upload-version.jpg makes the workflow auditable and prevents accidental loss of the original.
If something still looks wrong
Return to the original source instead of piling more edits onto the current export. Most document-photo problems are easier to solve upstream than at the end of a compression chain.
Keep the workflow reversible
Preserve the source image and make separate application versions. Reversible workflows are safer because a changed requirement does not force you to start with a damaged or repeatedly compressed file.
Practical detail to carry forward
If this is a repeated task, write the destination into your notes next to the final dimensions. A small record is surprisingly useful when the same person later needs another application photo.
Why Passport Portals Reject Correctly Sized Photos
Confirm the current authority instructions first. Then use the Studio to produce the matching image without changing the person unnecessarily.