A prenup is meant to be signed before marriage. In South African legal language, the document is usually called an antenuptial contract or ANC. If you are already married, you generally cannot fix the position by simply signing a normal prenup afterward.
That does not always mean nothing can be done. It means the route is different, more formal, and usually requires legal advice.
The short answer
If you are not yet married, arrange the antenuptial contract before the wedding. If you are already married and want to change your matrimonial property system, you are no longer dealing with a normal antenuptial contract. You are dealing with a post-marriage change to the marital regime.
In many cases, that requires a court-approved process rather than a private agreement signed between spouses.
What did the Constitutional Court say in 2026?
In VVC v JRM and Others [2026] ZACC 2, the Constitutional Court confirmed that spouses could not use an ANC signed during an existing customary marriage to change their matrimonial property regime without following the court-supervised route. An extra-judicial agreement that effectively changes the regime is not a substitute for the required process.
Section 21 of the Matrimonial Property Act 88 of 1984 provides for a joint application to court. The court must be satisfied that there are sound reasons for the change, sufficient notice has been given to creditors, and no other person will be prejudiced. The court may then authorise a notarial contract regulating the future matrimonial property system. The application of this route depends on the marriage and the facts, so tailored legal advice is important.
Why timing matters
The timing of the contract matters because the marriage itself creates legal consequences. If spouses marry without an ANC, the default position is usually marriage in community of property. If the spouses wanted to marry out of community of property, they should have signed the ANC before the marriage.
Trying to change the position afterward is not the same as choosing correctly before the wedding.
What if the wedding has not happened yet?
If the wedding has not happened yet, act immediately. You may still be able to sign an ANC before the marriage, depending on the time available and the complexity of the facts.
Read how long an antenuptial contract takes and the prenup checklist before you sign.
What if you are already married?
If you are already married, get legal advice before assuming the position is impossible or simple. A post-marriage change to the matrimonial property system is a formal legal issue. Where section 21 applies, it requires a joint court application, sound reasons for the proposed change, sufficient notice to creditors, no prejudice to another person, and a properly executed notarial contract if the court grants authority.
For a full legal route, read SD Law’s guide to postnuptial agreements in South Africa.
Common situations
| Situation | Likely route | What to do |
|---|---|---|
| Wedding is still ahead | Normal ANC may still be possible | Act urgently and speak to a notary or attorney. |
| Already married without an ANC | Post-marriage regime change | Get legal advice on the court route. |
| ANC was signed but registration is in question | Technical/legal review needed | Get advice before assuming the contract is valid or invalid. |
| One spouse now has business or debt risk | Urgent legal planning | Speak to an attorney before creditors or transactions complicate the position. |
Do not rely on a private document alone
A private agreement between spouses may not change the matrimonial property system in the way people expect. If the legal regime needs to change after marriage, it must be handled through the correct legal process.
This is especially important where creditors, immovable property, business interests, inheritances, trusts or children from a previous relationship are involved.
Related prenup guides
- Types of marriage contracts in South Africa
- How long does an antenuptial contract take?
- Prenup cost in South Africa
- ANC with accrual vs without accrual
FAQ: signing a prenup after marriage
Can we sign a prenup after we are married?
Not as a normal antenuptial contract. If you are already married, a private agreement does not by itself change the existing matrimonial property system. Where section 21 of the Matrimonial Property Act applies, spouses must jointly obtain court authority for the change and the future notarial contract.
What is a postnuptial agreement?
In everyday language, people use “postnup” to describe a post-marriage arrangement. In South Africa, changing the matrimonial property system after marriage is a formal legal process and should be handled by an attorney.
What if we signed an ANC but it was not registered properly?
Get legal advice. Late registration or validity questions are technical and should not be handled by assumption.
What if the wedding is next week?
Act immediately. It may still be possible to deal with the ANC before marriage, but timing, signing logistics and complexity matter.
General information only. This page does not replace legal advice on a post-marriage regime change.