Is there anybody out there who can tell me the maximum age for a dependent child's "O" visa? I have 2 sons who are completing their education as best they can here (home schooling), but due to circumstances there have been delays. They both want to study at university once their schooling is complete, but the age restriction is looming. There is no way that they can be sent to any international school, I'm a lowly schoolteacher. Thanks in advance.

We really need to know your visa/extension of stay status. If section 7.6 extension of stay for work as a teacher the age under section 7.18 for dependents is below age 20.

There is no age limit for ED type visas/extensions of stay.