Hello regarding 90days report - my son is 5years old, and will be late to report just for 3days since the immigration will be closed for APEC. Does the child also need to pay the penalty same as adults?

And what can I do if the adult’s 90days report got accepted but child’s one rejected when I put the exactly same information there? When I go to the immigration to claim it the due is already passed(+96days)

TIA