3 How can the spouses arrange their property regime?

3.1. Which provisions can be modified by a contract and which cannot? Which matrimonial property regimes may be chosen?

The spouses have the possibility of agreeing, via a marriage contract, to a different matrimonial property regime than the legally-provided separation of property. But not all proprietary agreements between the spouses are regarded as marriage contracts - one only speaks of them when they largely replace the legal matrimonial property regime and are intended to comprehensively regulate the economic relations.
As alternative forms of matrimonial property regime Austrian law provides the community of property and the contract of inheritance. However, the spouses do not have to restrict themselves to these in their choice of a matrimonial property regime.
With regard to the community of property regime, two forms have to be distinguished: the legally unregulated community of property inter vivos and the community of property in the event of death. The community of property inter vivos can be structured as a universal or limited community of property. In the first case, the entire brought-in and future property of the spouses is covered by the community of property, in the second case only certain assets enumerated in the marriage contract are incorporated. The spouses become co-owners of the common assets, their (ideal) shares are determined by the agreement - in case of doubt, it is assumed that their shares are equal in size. Between the spouses internally effective restraints on disposition with regard to the co-owners’ shares exist, which are not opposable to third parties. Opposability to third parties only exists in the case of a prohibition on alienation and/or encumbrance recorded in the land register under § 364c ABGB, or if reference is made to the restraint on disposition when the co-ownership is recorded.
Under the community of property inter vivos, both the community property and the personal property of the individual spouses is liable for common debts. . If one spouse incurred the liabilities alone or they otherwise concern him/her personally (e.g. obligations to pay maintenance or damages), under the universal community of property regime, the entire community property as well as his/her personal property are liable. In case of the limited community of property regime, by contrast, the non-debtor spouse does not have to answer for such debts with his/her share of the community property.
Under the community of property in the event of death, the separation of property remains in place until the death of one of the spouses, each can dispose freely of his/her assets. If one spouse dies, the assets of the spouses are united into a community property, which after deduction of debts will be divided into two halves. The surviving spouse receives one half, while the other half forms the estate of the deceased (§ 1234 ABGB).
Under the contract of inheritance, one spouse designates the other or both designate each other reciprocally as heirs (§ 1249 ABGB). However, only three-quarters of the estate may be covered by such a contract (§ 1253 ABGB).

In addition to these there are also advance agreements, which settle the division of the marital property of daily use, the marital savings and/or the marital home in case of divorce in advance. The principle of the separation of property during marriage remains unaffected by these agreements. The judge can depart from an effective advance agreement only if one spouse is unfairly disadvantaged and it would be unreasonable to impose the division arrangement on him/her (§ 97 para. 2 Ehegesetz, EheG).

3.2. What are the formal requirements and who should I contact?

Marriage contracts and advance agreements concerning the division of the marital savings and the marital home must be concluded in the form of an authentic instrument (§ 97 para. 1 EheG). In these cases, therefore, the conclusion of a contract must be executed by a civil law notary. By contrast, advance agreements on the division of the marital property of daily use merely require written form (§ 97 para. 1 EheG).

3.3. When may the contract be concluded and when does it come into effect?

Marriage contracts and advance agreements can be concluded at any time during marriage. Marriage contracts that are concluded prior to marriage apply only under the condition of the later marriage. In conformity with their purpose, marriage contracts and advance agreements become effective either immediately (e.g. an agreement of a community of property inter vivos) or only upon the death of a spouse (community of property in the event of death) or as of the divorce (advance agreements).

3.4. May an existing contract be modified by the spouses? If so, under what conditions?

The spouses can also modify an existing agreement, provided that the formal requirements are fulfilled.