Reasons to Revise a Will
One of the more common reasons a person revises a will is when a change in family status—marriage, divorce, or birth of a child—takes place (see the FreeAdvice article When and How Should I Revise My Will?), but there are a number of other situations that may warrant a change to a will.
Changes in Financial Situation
If you lose or change jobs, and your income and benefits are affected enough to change the value of your estate significantly, either up or down, you will need to write a new will. Another scenario requiring you to change your will might be if you come into so much money that it changes the value of your estate significantly, such as win the lottery, inheriting money, hitting it big in the stock market, or buying or sell real estate.
Always make sure your will realistically reflects your current situation.
Because laws vary from state to state, you'll want to revise your will if you move to make sure your beneficiaries still receive the property or gifts you intend for them. For example, if you are married and you move from a community property state to a common law property state, or vice versa, what you and your spouse own may change so you need to check with an estate attorney. If the laws are no different in your new state, a codicil changing your present address should be sufficient.
Witness/Executor/Beneficiary/Guardian Dies or Changes
Witnesses: If one of the witnesses to your will passes away, your will will only be affected if it is contested after you die. In that case, a judge may, ask for sworn, notarized statements or affidavits from anyone with knowledge of the circumstances of the will's execution, since the deceased witness will not be able to testify. If your witnesses signed a self-proving affidavit, that should suffice in lieu of courtroom testimony. (See What if a Witness to the Execution of a Will Dies?). You do not need to revise your will if one of your witnesses passes away.
If you want a different witness, you will need to write a new will and execute it before two (or three, in Vermont) witnesses.
Executor: The executor of your will has the important job of making sure your wishes are carried out. If you discover that the person or institution you initially named may not be the best person for the task, or if that person dies, you can name a new executor by using a codicil.
Beneficiaries: If one of your beneficiaries dies or you simply want to change a beneficiary, you can amend your will by codicil, naming the new beneficiary to take the place of the previously named one.
Guardian: If the guardian you nominated to care for your children dies, or you have changed your mind about the person you originally chose, you can amend that choice with a codicil.