Writing a will is one way that you can have a say in how your property is distributed after you pass away. However, you are not entirely free to distribute your property any way that you want. The law normally provides that your spouse receive at least a share. How much money you can leave to a sibling instead of your spouse depends on your state's laws.
Community Property States
A minority of states treat marital property as community property. This means that any money acquired during the marriage and anything purchased with that money belongs equally to both spouses. If you don't have a will, all of the property automatically goes to your surviving spouse. In a will, you can ordinarily leave up to 50 percent of the property to someone else, such as a sibling. There are exceptions, however, for some types of property, including the family home. Generally, the spouse can continue to live in the house as long as it's a primary residence, but the spouse's ownership interest is only half. Whatever you put in a will, your spouse will get at least half of the community property. On the other hand, money and property you had before the marriage, or that you inherit individually, is typically your individual property to distribute however you want, especially if you maintained separate ownership during your marriage.
Common-Law Property States
Most states have a property law system inherited from the common law of England. In these states, money that you acquired during the marriage on your own is your separate property. With a few exceptions, you can distribute this money however you want in your will. You and your spouse can also hold money and property jointly. Your right to leave this money in a will to a sibling depends on the legal way in which you and your spouse own the property. If you own it as "joint tenancy with right of survivorship" or "tenancy by the entirety," the property automatically goes to the surviving spouse. If you own it as "tenancy in common," then half goes to your spouse automatically and you can distribute the other half as you want, subject to homestead exemptions that allow a spouse to continue living in the family home. Money that you jointly earned, such as in a joint business venture, can be more problematic. Ask a lawyer in your state how the state treats this money in the absence of a legal document.
Spousal Elective Share
In common law property states, your spouse has the option to either take what was left to him in the will or to take a statutory share of your estate. Traditionally, your spouse is entitled to 33 percent of your entire "augmented estate," which includes the joint property and any property you gave away by other methods than using a will, such as gifts or trusts. The exact percentage of the spousal elective share varies from state to state. The Uniform Probate Code uses a formula based on how long you and your spouse have been married and some states have similar provisions. If you want to leave money to your sibling instead of your spouse, you should make sure that you leave at least the elective share amount of property to your spouse.
Pretermitted Spouse Share
Some states, such as Florida, follow a common-law doctrine called "pretermitted spouse share." Under this doctrine, if you wrote a will prior to marriage and did not amend the will after marriage to leave property to your spouse, the law assumes that was an oversight on your part. Your spouse is then entitled to the amount of your estate that she would be entitled to had you not left a will at all. This amount is set out by statute and is often different from the percentage of the elective share. The percentage varies between states.