If you're a U.S. resident or citizen who is making the leap to living in Australia permanently, you've got a lot of work ahead of you. It's all doable, but write down everything lest you forget, because you're going to find that more and more of your life needs to be redone and restructured. Estate planning is one of these areas. Even if you don't intend to change beneficiaries, you have to be sure that your estate planning documents are legal under Australian law. If there is ever a dispute, your heirs will be grateful you got everything in order.
Your U.S. Will Might Not Cover Your Australian Personal Property
Let's make this a little easier and say that you're renting your home here, own a car, and otherwise don't have much in the way of property. Your savings are in basic accounts. You'd think that those might be covered under your U.S. will and/or trust, but not necessarily. Australia has a probate process, too, and you want to be sure that you've set up your accounts here and protected your property here from Australian probate in addition to American probate processes. Limits may be different, and the types of property covered or not covered by probate may be different, too.
Your Beneficiaries Here May Have U.S. Taxes to Deal With
If you leave money or goods to heirs here in Australia, especially if the money or property is located in the U.S. (for example, money in a U.S. bank account), your heirs here might have extra taxes to deal with as they move the money from the U.S. to Australia. They should not attempt this without the help of a tax attorney, unless your attorney in Australia has already made it clear what might be taxed.
Basic Power of Attorney Regulations May Require Different Forms and Wording
Power of attorney exists in Australia just as it does in the U.S., but never, ever assume that your U.S. documents will be good in Australia. Wording may differ, you may need to have the person added to certain accounts, and the person may have different abilities here with a power of attorney than they would in the states. If that sounds vague, it's because all of the different states in the U.S. have their own approaches to estates and power of attorney.
If you immigrate to Australia, meet with an estate planning attorney as soon as you get settled. It might not seem like an urgent matter to you, but it's something that your heirs will be grateful you addressed. Look into how wills work for more information.