The passport rule, as published
The defector-day listing states it most directly: a current valid passport is required on the day of travel, and you do not need to send a copy when booking. The small-group listing requires a phone number with country code so the operator can reach you around access windows. Neither is bureaucracy for its own sake — the DMZ's checkpoints are operated by the military, and tour operators are admitted under conditions that can change with the security situation. Bring the physical passport; a photo on your phone does not satisfy the listings' stated requirement.
Access rules also shape what you can carry and photograph at the sites, and conduct rules apply at Imjingak's memorials, which Visit Korea's guide describes as a unification and security tour complex a few kilometres from the DMZ. Follow the guide's instructions on the day; they are the operator's access guarantee.
Book with the rules in mind
Because identity and access rules can change, the safe sequence is: read the listing's current restrictions at booking, send the operator your details exactly as asked, and re-read the confirmation email the week of the tour. If a member of your party is a non-Korean passport holder with a visa rather than a permanent residence document, ask the operator explicitly — the listings checked here do not publish a visa-type matrix, and this site will not guess one.
For the tunnel the rules protect, see the tunnel-walk guide; for what happens when access changes, see the changes guide.
Common questions
Do I need to submit my passport in advance?
No — the checked listings state a passport is required on the day of travel and no copy is needed at booking. Requirements can change, so reconfirm at checkout.
Are foreign visitors allowed on DMZ tours?
The checked listings operate international tours and publish no nationality restrictions. Ask the operator directly about any unusual passport or visa situation before booking rather than assuming.