Upon the death of the testator (decedent), their entire estate, including assets and liabilities, forms a legal entity known as the estate. The estate consists of movable and immovable properties, bank accounts, company shares, cryptocurrency assets, intellectual property rights (such as trademarks and patents), receivables, and debts. Heirs jointly own the estate under joint ownership from the moment of the testator’s death. This means that the rights within the estate remain undivided among the heirs until a formal sharing takes place.

Managing an estate under joint ownership can be quite challenging. In legal practice, one of the most common disputes among heirs arises from this issue. To resolve such disputes and to terminate joint ownership, Articles 676 and subsequent provisions of the Turkish Civil Code ("TCC") allow heirs to enter into an inheritance sharing agreement. The validity of such an agreement is subject to certain legal requirements.

This article examines the details of an inheritance sharing agreement, which enables the division of estate assets or their conversion into shared ownership.

1. The Inheritance Sharing Agreement Must Be Established After the Death of the Testator

Heirs acquire their inheritance rights upon the death of the testator. As of the moment of death, heirs automatically obtain joint ownership over the testator’s estate without requiring any additional legal process. Since inheritance rights do not exist before the testator's death, any inheritance sharing agreement made among heirs before this time is deemed invalid.

However, if the testator has given consent or is a party to the agreement, it may be considered valid. If an invalid inheritance sharing agreement is made before the testator’s death, the parties may demand the return of any assets transferred under the agreement.

2. All Legal and Appointed Heirs Must Be Parties to the Agreement

A fundamental requirement for a valid inheritance sharing agreement is the participation of all heirs. This includes both legal heirs (heirs recognized by law) and appointed heirs (heirs designated by the testator through a will or other legal instruments). If any heir does not become a party to the agreement, the agreement is deemed invalid.

If any of the heirs are legally incapacitated, their legal guardian may participate in the agreement on their behalf. However, this requires prior approval from the guardianship authority.

3. The Inheritance Sharing Agreement Must Be in Written Form

For the agreement to be legally valid, it must be in written form. This is a formal requirement, meaning that an oral agreement is not legally binding. The required written format is a simple written agreement; it does not have to be notarized or handwritten. However, for ease of proof in case of legal disputes, having the agreement notarized is highly recommended.