Forced heirship is a form of testate partible inheritance which mandates how the deceased's estate is to be disposed and which tends to guarantee an inheritance for family of the deceased.

In forced heirship, the estate of a deceased (de cujus) is separated into two portions.

Forced heirship is generally a feature of civil-law legal systems which do not recognize total freedom of testation, in contrast with common law jurisdictions.

Normally in forced heirship, the deceased's estate is in-gathered and wound up without discharging liabilities, which means accepting inheritance includes accepting the liabilities attached to inherited property. The forced estate is divided into shares which include the share of issue (legitime or child's share) and the spousal share. This provides a minimum protection that cannot be defeated by will. The free estate, on the other hand, is at the discretion of a testator to be distributed by will on death to whomever he or she chooses. Takers in the forced estate are known as forced heirs.

The expression comes from Louisianan legal language and is ultimately a calque of Spanish sucesión forzosa.

Forced heirship laws are prevalent among civil law jurisdictions; these include major countries such as Brazil, France, Germany, Italy, Spain, Switzerland, and Japan. Reckoning shares in instances of multiple or no children and lack of surviving spouse vary from country to country. In Germany, for example, a forced heir receives at least half of what they would have received in the absence of a testament.

In Islamic law, as practiced for example in Saudi Arabia, forced heirship is the rule and testaments are fairly rare. A testator may distribute at most a third of their legacy and only to persons outside the circle of regular heirs (meaning for example that one son can never inherit more than another).

Advocates of forced heirship contend that it is perfectly proper for testators to be required to make adequate provision for their dependants, and that most countries in the world permit wills to be varied where they would leave dependants destitute. Critics suggest that there is a great difference between varying wills to the minimum degree to provide sufficient financial support for dependants, and prohibiting the testator from distributing the estate or a proportion of the estate to any female children, or younger male children, and that it cannot be any less repugnant to force a deceased person to distribute their assets in a certain manner on their death than it would be to tell them how they may do so during their lifetime.^{[citation needed]}