Making a will is especially important for people with young children, because wills are the best way to transfer guardianship of minors.
You may amend your will at any time. In fact, it’s a good idea to review it periodically and especially when your marital status changes. At the same time, review your beneficiary designations for your 401(k), IRA, pension and life insurance policy since those accounts will be transferred automatically to your named beneficiaries when you die.
A will is also useful if you have a trust. A trust is a legal mechanism that lets you put conditions on how your assets are distributed after you die and it often lets you minimize gift and estate taxes. But you still need a will since most trusts deal only with specific assets such as life insurance or a piece of property, but not the sum total of your holdings.