I wish to bequeath a sum of money to my grandson. Will he benefit from the €31,865 tax allowance?

No. The €31,865 allowance applies only to gifts made during the donor’s lifetime by grandparents to their grandchildren, as provided under Article 790 B, paragraph 1 of the French General Tax Code. In the context of inheritance, your grandson will only benefit from a €1,594 allowance, which is the standard abatement for inheritances received from ascendants other than parents.