A will can be changed at any time by its author alone. A contract of succession, by contrast, is a binding agreement: the contracting parties declare their intentions simultaneously before a notary and two witnesses. It can be cancelled by a written agreement of all parties involved.
A contract of succession can be used to appoint heirs, determine legacies or agree on waivers of inheritance, for example when a child waives their compulsory portion because they have already received a business during the lifetime of the deceased. Since 2023, gifts that are incompatible with the obligations under the contract of succession can be challenged, with the exception of customary occasional gifts.