South Dakota Prenuptial Agreement

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Connolly v. Connolly, 270 N.W.2d 44 (S.D. 1978)

The court invalidated an antenuptial alimony waiver as contrary to South Dakota public policy, establishing the categorical rule — still controlling today — that spousal support cannot be contracted away in a prenuptial agreement.

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Smetana v. Smetana, 2007 SD 5, 726 N.W.2d 887

The court invalidated an antenuptial agreement where the husband provided no list of assets or liabilities at any time, holding that general courtship-era awareness of asset categories is insufficient disclosure without an approximate net worth figure that also captures liabilities.

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In re Estate of Eichstadt, 2022 SD 78, 983 N.W.2d 572

The court found a premarital agreement involuntarily signed where the wife had limited education, no independent counsel, was brought to the drafting attorney's office without prior notice of the prenup, and credibly testified she did not understand what she was signing.

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Sanford v. Sanford, 2005 SD 34, 694 N.W.2d 283

The court voided the alimony waiver in a prenup between a $55M-net-worth husband and a $127,500-net-worth wife but enforced the property division provisions, holding that an invalid spousal support clause is severable from otherwise valid property terms when the agreement contains a savings clause and property protection was clearly the agreement's core purpose.

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In re Estate of Smid, 2008 SD 82, 756 N.W.2d 1

The court enforced a premarital agreement where the surviving wife claimed she signed only to "avoid probate," holding that voluntariness requires a totality-of-circumstances analysis and that failing to fully read or understand an agreement — absent fraud or coercion — does not render execution involuntary.

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In re Estate of Webb, 2026 SD 2

The court enforced a prenuptial agreement presented to the wife the day before the wedding, distinguishing Eichstadt on the grounds that the wife held a college degree, had business management experience, actively engaged with the document's asset schedules, and had a meaningful opportunity to seek independent counsel.

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1. Is a prenuptial agreement enforceable in South Dakota?

Yes. South Dakota prenuptial agreements are enforceable under the Uniform Premarital Agreement Act, SDCL §§ 25-2-16 through 25-2-25, enacted in 1989. The agreement must be in writing, signed by both parties, entered into voluntarily, and accompanied by fair and reasonable financial disclosure (or a written waiver of disclosure). South Dakota is notably pro-enforcement: courts assess unconscionability only at the time of signing, not at divorce. If the agreement was legitimate when signed, it stands — the court will not revisit fairness based on how circumstances changed during the marriage.

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2. Can you waive alimony in a prenup in South Dakota?

No — and this is South Dakota's most critical departure from other states. Spousal support waivers, caps, and formulas are void as against public policy. The South Dakota Supreme Court established this rule in Connolly v. Connolly (1978) and reaffirmed it in Sanford v. Sanford (2005). When the legislature adopted the UPAA in 1989, it deliberately omitted the provision that would have allowed parties to contract over spousal support. Courts retain full authority to award alimony at divorce regardless of what the prenup says. Any alimony clause will be severed — but a strong severability clause protects the rest of the agreement. Many competing websites get this wrong; do not rely on sources that tell you SD allows alimony waivers.

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3. What happens if you divorce without a prenup in South Dakota?

South Dakota is an "all-property" equitable distribution state under SDCL § 25-4-44. This makes divorcing without a prenup riskier here than in most states. Without a prenup, every asset you own — including property you brought into the marriage, inheritances, gifts, family farms, and business interests — is subject to equitable division by the court, regardless of title or origin. There is no automatic "separate property" exemption. The court divides everything based on factors like marriage length, each spouse's contributions, earning capacity, and the income-producing capacity of assets. A prenup is the only reliable way to keep specific assets off the table.

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4. Can a prenup protect a farm, ranch, or family business in South Dakota?

Yes, and this is one of the most important uses of a prenup in South Dakota. Without one, South Dakota's all-property rule puts farms, ranches, and businesses brought into the marriage at risk of equitable division at divorce — regardless of title, origin, or how many generations the property has been in one family. A prenup can designate these as separate property, specify how appreciation in value is treated, and prevent a divorcing spouse from claiming an ownership stake. The prenup must include an asset schedule listing the property and its approximate value at signing. For multi-generational agricultural operations, this is essential estate and succession planning.

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5. Does a prenup need to be notarized in South Dakota?

No. Notarization is not required by statute — SDCL § 25-2-17 requires only that the agreement be in writing and signed by both parties. However, notarization is strongly recommended. It creates a presumption of authenticity, makes it harder to later claim a signature was forged or coerced, and adds a procedural layer courts view favorably when evaluating voluntariness. Both attorneys can notarize at the signing ceremony at no additional cost. Given how inexpensive notarization is relative to the protection it provides, there is no reason to skip it.

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6. Does South Dakota require a lawyer for a prenuptial agreement?

No — independent legal counsel is not required by statute. But it is one of the most important factors courts weigh when a prenup is challenged. South Dakota uses a totality-of-circumstances test for voluntariness (In re Estate of Smid, 2008), and the absence of counsel — especially combined with any education gap or power disparity — significantly increases challenge risk. In Eichstadt (2022), the court invalidated an agreement partly because the wife had no independent attorney and only an eighth-grade education. Both parties should have their own separate counsel. The cost of a review is trivial compared to the cost of a successful challenge.

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7. How far in advance should a prenup be signed in South Dakota?

South Dakota has no statutory minimum, but timing is one of the most litigated challenge grounds. Best practice is to sign 60+ days before the wedding, with both parties having 2–3 weeks to review the final draft. Start discussions with an attorney 4–6 months before the wedding. That said, In re Estate of Webb (2026) shows that even a prenup presented the day before the wedding can be enforced — the court upheld the agreement because the wife was college-educated, had business experience, actively engaged with the asset schedules, and had a meaningful opportunity to seek counsel. Timing alone doesn't determine voluntariness, but signing early eliminates the argument entirely.

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8. How much financial disclosure is required in a South Dakota prenup?

"Fair and reasonable disclosure" of assets and financial obligations is required under SDCL § 25-2-21, or a written waiver of further disclosure. Courts do not require exact figures — an approximate net worth schedule listing assets and liabilities with reasonable valuations satisfies the standard (Sanford, 2005). In Smetana (2007), the court invalidated a prenup where the husband never provided any list of assets or liabilities, holding that general courtship-era awareness of asset categories is not enough without an approximate net worth figure. Critically, liabilities must be disclosed, not just assets. Omitting debts is one of the most common and fatal drafting errors.

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9. How do South Dakota courts decide if a prenup is invalid?

Under SDCL § 25-2-21, the challenging party must prove either: (1) the agreement was not executed voluntarily, or (2) the agreement was unconscionable at execution AND the challenging party was not given fair disclosure, did not waive disclosure in writing, and lacked adequate independent knowledge of the other party's finances. Both elements of prong 2 must be met — unconscionability alone is not enough, and lack of disclosure alone is not enough. Crucially, unconscionability is judged only at the time of signing, not at divorce. Courts do not re-examine fairness based on changed circumstances during the marriage, which makes South Dakota one of the more prenup-friendly states on enforcement.

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10. Can a prenup protect an inheritance in South Dakota?

Yes — and it's more important here than in most states. South Dakota is an all-property state, meaning inherited assets (whether received before or during the marriage) are technically subject to equitable division by a court at divorce. There is no automatic statutory protection for inherited property. A prenup can expressly designate inheritances as separate property, exclude them from the marital estate, and ensure they pass to children from prior relationships or remain within the family. Without a prenup, a court could award part of an inheritance to the other spouse, particularly in a long marriage.

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11. Can you get a postnuptial agreement in South Dakota?

South Dakota does not have a specific postnuptial agreement statute, but courts apply similar principles to postnuptial agreements as they do to prenuptial agreements — voluntary execution, fair disclosure, and non-unconscionable terms. The key difference: postnuptial agreements face a somewhat higher standard of scrutiny because the parties already owe each other fiduciary duties as spouses. If you missed the window for a prenup, a postnuptial agreement is still significantly better than no agreement. It can address property classification, debt allocation, inheritance protection, and asset management during the marriage. It still cannot waive or modify spousal support.

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12. Does a South Dakota prenup protect you from your spouse's debt?

Yes. A prenup can allocate responsibility for premarital debts so that each party remains responsible for their own obligations brought into the marriage. It can also specify how debts incurred during the marriage are treated — for example, that debts titled solely in one spouse's name remain that spouse's responsibility. This is particularly important in South Dakota's all-property system, where without a prenup, a court could factor one spouse's debts into the overall equitable division in ways that disadvantage the other. Note that a prenup does not override creditor rights — it governs the allocation between spouses, not what a creditor can collect.

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13. Is a prenup worth it if you're getting married in South Dakota?

In South Dakota, a prenup delivers more value than in most states because of two features of SD law. First, South Dakota is an all-property state — without a prenup, everything you own, including pre-marital assets, inheritances, and family businesses, is subject to division at divorce. There is no automatic separate-property protection. Second, South Dakota prohibits spousal support waivers in prenups, so alimony risk at divorce cannot be contracted away. A prenup eliminates the property-division risk entirely. Facing only potential alimony exposure at divorce — with all assets fully protected — is dramatically better than facing alimony plus full asset division with no protections at all.

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14. Do you need a prenup for a second marriage in South Dakota?

A prenup is particularly valuable for second (or subsequent) marriages in South Dakota. Most people entering a second marriage have accumulated more assets, may own a home or business, and often have children from a prior relationship whose inheritance they want to protect. Without a prenup, South Dakota's all-property rule puts all of those assets at risk in a future divorce. A prenup can also waive each spouse's elective share of the other's estate under SDCL § 29A-2-213 — protecting your estate plan and ensuring assets pass to your children rather than a surviving spouse. The Webb (2026) case specifically involved a second marriage where the court enforced the prenup's waiver of the elective share.