Here's when you should take a second look at your estate plan:
More important than an occasional review is changing your estate plan along with your life. Marriage, divorce, the birth of a new child, the death of a close friend: these are the exact sort of events that should trigger another look at your Last Will and Testament. Obviously, taking care of your legal paperwork isn't top of mind when you're planning your honeymoon, say, but when you get back, why not sit down with your new spouse and plan for the future?
Periodic reviews are important, since you may have accumulated some important assets between the time of writing your Will and the present. Perhaps you inherited some land or purchased a car or started your own business. Alternatively, perhaps you've liquidated some assets and a certain heir would now be left with nothing. Rereading your estate plan once every three to five years will catch those issues and allow you to make your Will and other important documents current.
How you change your estate plan depends largely on what documents you need to make current. Commonly, people will file something called a Codicil to Will, which replaces old clauses in your Will with new ones. This is great when you're adding a grandchild to your beneficiaries or removing a certain item or asset from your Last Will.
When you're thinking about wholesale changes, such as those that might occur after a marriage, give serious consideration to creating a new Will. While it sounds like a lot of work to start from scratch, remember two things. First, you've already created a Will and being familiar with the process will make the second time go that much quicker. More importantly, the big life changes that prompt a new Will often necessitate making similarly big changes to your estate planning documents. Rather than going through each one and possibly forgetting or missing something, starting over gives you the peace of mind that everything's sorted out just the way you want it.
Living Wills, Trusts, and Powers of Attorney function similarly. Sometimes, a simple amendment can be made, while other times, a wholesale redo is in order. Consult with an experienced estate planning attorney before you get started.