A waiver of an inheritance can have many reasons. Potential heirs thus contractually agree to waive their compulsory share - often in return for a severance payment.
In return, you waive your right to inheritance. You no longer have anything to do with the distribution of assets after the will has been opened. The only way to reverse it is with a termination agreement. But an agreement must be reached between the testator and the renouncer, which must be certified again by a notary. Notaries usually charge double fees for certifying a waiver of inheritance compared to the usual conditions. You can use the notary cost calculator on the Federal Chamber of Notaries website to find out how high the fees are. This depends on the amount of assets that are to be forgone. If you then row back again, you will incur additional costs. If a contract is signed, it can no longer be revoked. However, the person giving up should think carefully about whether and at what price they want to give up their share.