Postnuptial Agreements in South Dakota in SD — Family… | CGMIMM
Family Law · SD
Postnuptial Agreements in South Dakota
South Dakota postnuptial agreements are signed AFTER marriage but otherwise function like prenups — defining property division, alimony, and other financial terms in case of divorce.
Published May 8, 2026
## Postnuptial agreements in South Dakota
A **postnuptial agreement ("postnup")** is the same idea as a prenup — but signed AFTER marriage. They've become more common as couples deal with changing financial circumstances, second marriages, or relationship-strengthening efforts.
## Why couples sign postnups
**1. Inherited / new wealth.** One spouse receives substantial inheritance / business interest after marriage; couple wants to clarify ownership.
**2. Career changes.** One spouse leaves career to raise children; couple wants to address future support if marriage ends.
**3. Financial fresh start.** After major financial event (bankruptcy, business sale, lawsuit win) couple wants new framework.
**4. Reconciliation after separation.** Marriage troubled but reconciling; couple uses postnup as foundation for new commitment.
**5. Estate planning.** Particularly for blended families (children from prior marriages); ensures property goes to designated children.
**6. Business considerations.** One spouse owns business; postnup protects business from divorce-related disruption.
**7. Couldn't get prenup.** Prenup wasn't possible due to time constraints / cold feet; couple wants to retroactively cover same ground.
**8. Major change in roles.** Stay-at-home parent returning to work, or vice versa.
## Heightened scrutiny vs prenups
Postnups face **higher scrutiny** than prenups in most states because:
- Spouses already owe each other fiduciary duties
- Marital assets already exist
- Power dynamics may already be imbalanced
- The risk of coercion ("sign or I'll divorce") is greater
- Some states view postnups skeptically as encouraging divorce
Some states are particularly tough on postnups: OH (only validates with "unimpeachable" fairness), AL, IA. Others approach more neutrally.
## Common requirements
Most states require:
- **Written agreement**
- **Signed voluntarily** (no coercion)
- **Full and fair financial disclosure** (mutual)
- **Independent legal counsel** (strongly recommended; required in some states)
- **No unconscionability** at execution
- **No fraud / duress / mistake**
- **Substantive fairness** at enforcement (in some states)
- **Compliance with state-specific procedural rules**
## What a postnup CAN do
- Define separate vs marital property going forward
- Override default community-property or equitable-distribution rules
- Modify or waive alimony / spousal support
- Specify divorce property division
- Protect family business / inheritance
- Allocate debts
- Provide for children from prior relationships
- Address inheritance / estate planning
- Provide for blended-family considerations
## What a postnup CANNOT do
**Universal limits:**
- **Child support / custody** — best interests determined at divorce; can't be predetermined
- **Encourage divorce** — clauses creating financial incentive to divorce are unenforceable
- **Address non-financial matters** — chore lists, sex frequency, parenting style
- **Hide assets / commit fraud**
## Common provisions
- **Property classification** — what's separate vs marital
- **Property division** in case of divorce
- **Alimony / spousal support** terms
- **Estate / inheritance rights**
- **Business interest treatment**
- **Debt allocation**
- **Tax filing strategies**
- **Health insurance maintenance**
- **Sunset / review provisions**
## Independent counsel
**Strongly recommended** — sometimes legally required:
- Each spouse should have separate attorney
- Both attorneys negotiate / review
- Attorney's fees often paid by wealthier spouse
- Joint counsel CANNOT represent both spouses (conflict of interest)
- Some states (CA, MN) effectively require counsel
Without independent counsel, postnups are vulnerable to challenge.
## Common reasons postnups fail
- **Coercion** — "sign or I'll divorce"
- **Inadequate disclosure** — hidden assets
- **One-sided / unconscionable terms**
- **No legal counsel** for one spouse
- **Insufficient time** to review
- **Major change in circumstances** since signing
- **Fraud / duress / mistake**
- **Failure to comply with formalities**
## Reconciliation postnups
When couples reconcile after separation, the postnup may include:
- Forgiveness clause for past misconduct
- Specific commitments going forward
- Property allocations if reconciliation fails
- Counseling or treatment requirements
- Sunset provisions if marriage stabilizes
## Sunset / review clauses
Common to include:
- **Sunset** — agreement expires after X years
- **Periodic review** — both parties reaffirm or renegotiate every Y years
- **Triggering events** — automatic adjustments based on births, deaths, retirement
## Tax considerations
Federal Tax Cuts and Jobs Act (2017) eliminated alimony deduction for divorces after 2018 — affects postnup planning around alimony.
Marriage / divorce tax planning often integrates with postnups.
## Estate planning integration
Postnups frequently coordinate with:
- Wills
- Living trusts
- Beneficiary designations
- Life insurance
- Power of attorney
Without coordination, contradictory documents create chaos.
## What you should do
If you're considering a postnuptial agreement in South Dakota: don't draft it yourself. Each spouse should hire their own family-law attorney. Allow time for negotiation — rushed postnups face challenge later. Most South Dakota family-law attorneys offer flat-fee postnup packages.
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*This guide is general information about South Dakota law as of early 2026 and is not legal advice. Postnup law varies significantly. Talk to a licensed South Dakota family-law attorney about your specific situation.*
This guide is for general information only and does not constitute legal advice. Laws change and outcomes depend on your specific situation — talk to a licensed attorney before acting on anything you read here.