Do I have to notify me ex-spouse via registered mail when I move?

In Arizona there is a specific statute about what steps you must take if you wish to relocate more than 100 miles from the present address. Here is a link to the statute: http://www.azleg.state.az.us/FormatDocument.asp?inDoc=/ars/25/00408.htm&Title=25&DocType=ARS You should be aware that this statute may be changed by the legislature. If you are only moving a short distance I would suggest that you send the notice about changing your address both by registered and by regular mail. State on the letter that you sent it by both methods. If the registered letter comes back unclaimed, but the regular letter does not get returned, then that is evidence of receipt.

If you have custody of the children it is always advisable. Otherwise it depends on what the divorce agreement says.

For your own protection you should send it certified mail.

What does the order say? If it just says notify, then regular mail should be sufficient. If it says registered mail, then comply with the order.