A will sets out how a person wants his property distributed after death. When possible, the law enforces the deceased's intentions. If the beneficiary under a will is listed under a maiden name, the law assumes the deceased intended to leave the property to the person named, regardless of the name change. If the intent is clear, the will does not even need to use a correct or full legal name to leave property to a particular person.
Other Financial Instruments
Property can pass to others through a wide variety of instruments, including life insurance, trusts, payable on death accounts and retirement plans. If a beneficiary of one of these instruments is listed under her maiden name, she is still entitled to the benefit as she is still the same person. However, she needs to prove to the institution with control over the property, such as the life insurance company, that she is the person named.
To prove that you are the person named as a beneficiary, the best evidence that you can use is proof of the name change in a legal document. Your marriage certificate should have this information in most cases. If you cannot obtain a copy of your marriage certificate, sworn affidavits from neutral parties might be sufficient evidence in some cases. Life insurance companies and banks have their own procedures for proving who the beneficiary is when the name on file is not correct as in the case of a maiden name. You will need to follow the procedure of the specific institution.
The best practice is to change legal documents when the beneficiary changes her name. This leaves no doubt as to your intent and makes it easier for the beneficiary to receive a benefit from a private institution. It is often not necessary to change a will if the only change needed is to change a beneficiary's maiden name. However, as wills are a matter of state law, you should ask an attorney in your state what lawyers consider the best practice in your jurisdiction.