Everything engaged couples need to know about making a prenuptial agreement valid and enforceable in South Dakota — in plain English, reviewed by attorney James Sexton, Esq.
Yes — prenuptial agreements are legal and enforceable in South Dakota under the Uniform Premarital Agreement Act at SDCL Chapter 25-2, with one major carve-out for spousal support.
South Dakota adopted the Uniform Premarital Agreement Act at SDCL §§ 25-2-16 to 25-2-25. An agreement must be in writing, signed by both parties, and — a formality most UPAA states skip — executed and acknowledged or proved in the same manner as a grant of land (SDCL 25-2-16), which in practice means signing before a notary. It requires no consideration and takes effect on marriage. But South Dakota deliberately deviated from the model act: SDCL 25-2-18's list of permitted subjects omits spousal support, and in Sanford v. Sanford, 2005 S.D. 34, 694 N.W.2d 283, the state Supreme Court held that provisions waiving or limiting alimony are void as against public policy. Property terms are enforced; alimony stays with the divorce court.
A South Dakota prenup is enforceable when it is written, signed, acknowledged like a land grant, voluntary, and backed by fair disclosure — but any clause waiving spousal support is void, no matter how cleanly it was signed.
The agreement must be a written document signed by both parties and, under SDCL 25-2-16, executed and acknowledged or proved in the same manner as a grant of land — in practice, signed before a notary. It becomes effective upon marriage and needs no consideration.
A prenup is unenforceable if the challenging spouse proves it was not executed voluntarily. Signing well before the wedding is the simplest protection against a duress claim.
An agreement fails if it was unconscionable when signed and the challenger received no fair and reasonable disclosure, didn't waive disclosure in writing, and had no adequate knowledge of the other's finances.
Under SDCL 25-2-18 as read in Sanford v. Sanford, South Dakota prenups may not waive, limit, or fix alimony. Include a severability clause so the rest of the agreement stands untouched.
| Governing statute | Uniform Premarital Agreement Act — SDCL §§ 25-2-16 to 25-2-25 |
|---|---|
| Property division | Equitable distribution |
| Notarization | Required — executed and acknowledged like a grant of land (SDCL 25-2-16) |
| Waiting period | None required — but sign well before the wedding |
| Spousal support | Cannot be waived — alimony waivers are void (Sanford v. Sanford) |
See how South Dakota's signing formalities compare in our prenup notarization requirements by state guide.
South Dakota courts strike alimony-waiver clauses automatically, and set aside whole agreements only for involuntary signing or unconscionability paired with a failure of financial disclosure.
The Sanford court explained that the alimony rule isn't about paternalism — it protects the support rights of both spouses, and it means a South Dakota judge always retains the power to award support based on circumstances at divorce. Everything else follows the standard UPAA playbook: the challenger must prove the agreement was involuntary, or unconscionable and made without fair disclosure, adequate knowledge, or a written disclosure waiver. A voluntary, fully disclosed South Dakota prenup keeps its property terms intact even if an alimony clause is severed.
Trusted Prenup creates a state-specific South Dakota prenuptial agreement online — built to meet the requirements above and designed by James Sexton, Esq. A traditional attorney typically costs $2,500–$10,000; this is a flat $599.
A guided questionnaire captures your assets, debts, and wishes — most couples finish in under 90 minutes.
We assemble a complete prenup built to meet your state's exact legal requirements.
Review with your partner, then sign online with notarization handled for you.
A South Dakota attorney-drafted prenup generally costs $1,500–$5,000 or more. Trusted Prenup creates a state-specific South Dakota prenup online for a flat $599, with optional notarization and attorney-review add-ons.
Yes — SDCL 25-2-16 requires a premarital agreement to be executed and acknowledged or proved in the same manner as a grant of land, which in practice means signing before a notary. Trusted Prenup's online notarization add-on satisfies this at signing.
No. South Dakota is one of the few states that prohibits it: the Supreme Court held in Sanford v. Sanford (2005) that alimony-waiver provisions are void as against public policy under SDCL 25-2-18. Spousal support is decided by the court at divorce, based on circumstances at that time.
Yes, but the challenger must prove the agreement was signed involuntarily, or that it was unconscionable and made without fair financial disclosure, a written waiver of disclosure, or adequate knowledge of the other spouse's finances. Property terms in a clean, disclosed agreement hold up.
No — courts sever the void support provision and enforce the valid property terms, especially when the agreement includes a severability clause. A well-drafted South Dakota prenup is written with this rule in mind from the start.
Yes — property rights are exactly what SDCL 25-2-18 lets couples contract about, including land owned before the marriage and anything acquired during it. Keeping a farm, ranch, or business as separate property is one of the most common reasons South Dakota couples get a prenup.
Yes — South Dakota enforces properly executed prenuptial agreements regardless of how they were drafted. What matters is execution: a written agreement, voluntary signatures, full financial disclosure, and South Dakota's signing formalities. The full picture is in are online prenups legally binding.
Trusted Prenup is not a law firm and does not provide legal advice. This guide is general information about South Dakota law and not a substitute for advice from a licensed attorney about your situation.