If you die without leaving a valid Will then you are treated as having died ‘intestate’ and the ‘intestacy rules’ take place.
The intestacy rules are complicated and can result in your estate passing to people that you would not have wished to benefit. For example, your estate may pass to distant relatives who you have never met. Or you may have relatives who you have become estranged from who may also become substantial beneficiaries to your estate. The process of finding these family members can also be costly and take a long time.
Even if you have made a Will, if it has not been drafted correctly or did not account for particular events then your estate can result in a partial intestacy. In these cases, then not only can the above scenarios come into play, but it may also make your estate more complicated and difficult to deal with for your other beneficiaries.