9. June 2026

When a Will Gives Rise to Dispute: How to Challenge a Defective Will and How to Plan Ahead

The death of a loved one is usually a deeply impactful and painful experience. It is all the more distressing when, after the reading of the will, it becomes clear that one inherits less than expected or nothing at all. In practice, the need to challenge a will arises frequently, yet many fail to take the right steps at the right time. This article provides an overview of the most important instruments under the law of succession and the procedural pitfalls that can determine success or failure in a given case.

In addition to the will, the law recognizes the contract of succession as a further form of disposition. For the sake of simplicity, the term “will” is used uniformly throughout the following; the same principles apply to contracts of succession.

Starting Point: Testamentary Freedom – But Not Without Limits

Any person who has the capacity of judgement and is at least 18 years old may in principle freely dispose of his or her assets. However, this testamentary freedom is not unlimited: the law prescribes certain formal requirements, prohibits unlawful or immoral dispositions, and protects the closest relatives through the law on statutory entitlements. Where heirs with a statutory entitlement exist – namely descendants, the surviving spouse or registered partner – they have been entitled, since 1 January 2023, to at least one-half of their statutory succession rights.

When Does Someone Wish to Challenge a Will?

In practice, we typically encounter the following situations:

• Lack of capacity of disposition: The testator suffered from advanced dementia or another cognitive impairment and drew up a will that does not reflect their presumed free will.
• Defect of will: The will came about through error, deception or coercion by third parties.
• Formal defects: The will was not drawn up in formally valid manner, for example because essential requirements were not met in the case of a holographic will (e.g. missing signature) or because defects existed in the notarial authentication (e.g. improper performance of the witness function).
• Unlawfulness or immorality: A disposition may be inadmissible in substance, for example where a person of trust of an elderly testator systematically exploits that position and has themselves appointed as heir in an immoral manner (so-called inheritance fraud).
• Infringement of the statutory entitlement: The statutory entitlement has been disregarded, for example through the favoring of third parties or through lifetime gifts.

Depending on which of these grounds applies, a different legal instrument comes into play.

The Action for Declaration of Invalidity (Art. 519 et seq. CC): Overturning the Will

By means of an action for declaration of invalidity, a will may be declared wholly or partially invalid, for example because the testator lacked capacity of judgement at the time the will was drawn up, because the will came about through deception or coercion, because its content is unlawful or immoral, or because it has formal defects. If the action is upheld, the will falls away and either an earlier will or the statutory order of succession applies.

Any person with a succession law interest in the declaration of invalidity may bring the action – in particular statutory heirs, legatees or beneficiaries under an earlier will. The action should be directed against all persons who derive advantages from the challenged will. This is because the judgment has effect only as against the parties sued. Anyone who does not bring the action against all relevant beneficiaries risks the judgment remaining without effect as against the others. The question of against whom one must proceed is therefore one of the first and most important decisions to be made.

The Action in Abatement (Art. 522 et seq. CC): Enforcing the Statutory Entitlement

The action in abatement comes into play where the statutory entitlement has been infringed. The will remains valid, but the dispositions contained therein are reduced to the extent necessary to preserve the statutory entitlement.

Any heir whose statutory entitlement has been infringed and who has not otherwise received the equivalent value of their entitlement – for example through a legacy or an inter vivos gift – may bring the action. The action is directed against the excessively favored persons. Anyone wishing to enforce their statutory entitlement in full should from the outset include all beneficiaries in the proceedings, since anyone who is not sued is not required to surrender anything.

How Much Time Is There, How Does One Proceed in Practice, and What Costs Are to Be Expected?

Strict forfeiture periods apply to both actions, which can neither be extended nor interrupted. Anyone who misses them irrevocably loses their right of action. From the time one becomes aware of the relevant circumstances, a period of one year applies. In the case of the action for declaration of invalidity, this period begins to run as soon as one learns of the will and of the ground of invalidity, but at the earliest from the death of the testator; in the case of the action in abatement, as soon as one knows of the death, of one’s own entitlement to a statutory share and of the infringement of that entitlement. The precise extent of the infringement need not yet be known. In addition, an absolute upper limit of ten years applies, regardless of when one becomes aware of the relevant circumstances. However, if the beneficiary acted in bad faith – i.e. knew of the invalidity or ought to have known of it – this period is extended to thirty years in the case of the action for declaration of invalidity.

The competent court is that of the last residence of the deceased. Before bringing an action, a conciliation procedure must first be initiated before the competent authority. The application for conciliation already preserves the time limit. Thereafter, three months remain to file the actual action.

Court costs are determined by the amount in dispute, i.e. the financial advantage the claimant would obtain upon success. The court requires an advance on costs, which may amount to up to one-half of the anticipated court costs. The party that loses the proceedings must generally also bear the opposing party’s legal costs. Particularly in the case of large estates, the costs can be considerable. In view of the emotional and financial burden involved, an early cost-benefit analysis is always advisable.

It is important to note that neither a judgment declaring a will invalid nor a judgment in abatement automatically results in performance. Anyone who, following a successful action, actually wishes to receive assets should therefore additionally, depending on the circumstances, bring an action for restitution, an action for recovery of inheritance, an action for delivery of a legacy or an action for division of the estate.

Practical Tips for Drawing up a Will: How to Prevent Disputes

• Draw up clear and formally valid dispositions: Formal defects are particularly common in practice and can be avoided with little effort. It is equally important that the directions be formulated clearly and unambiguously in substance.
• Consider a will by public deed: Particularly in complex circumstances, large estates, foreseeable family conflicts or where capacity of disposition is in doubt, a will by public deed provides greater legal certainty.
• Consider a no-contest clause: By means of a so-called no-contest clause, the testator may direct that a person who challenges the will shall receive nothing or only the statutory entitlement. Such clauses are generally permissible and can have a deterrent effect.

Practical Tips for Heirs Who Wish to Take Action

• Observe time limits: Claims under an action for declaration of invalidity and an action in abatement are subject to short, non-interruptible forfeiture periods.
• Choose the right action: If the issue is “only” an infringement of the statutory entitlement, the action in abatement is the correct instrument, not the action for declaration of invalidity. A wrong action will be dismissed; and the time limit for the correct one continues to run.
• Cost-benefit analysis: Succession disputes can be protracted and costly. A realistic assessment of the prospects of success before filing an action is therefore indispensable.

For further information, please contact:

Laura Mahler, Associate