South Dakota Community Property Trust: The Double Step-Up in Basis

South Dakota is a common law property state, meaning each spouse owns whatever is titled in their name. But since 2016, state law has offered married couples something usually reserved for community property states: a full step-up in tax basis on both halves of jointly held assets when one spouse dies.

This is one of South Dakota's most valuable estate planning tools, and most residents have never heard of it.

What the Step-Up in Basis Actually Means

When you sell an asset, you pay capital gains tax on the difference between what you paid (your "basis") and what you received. When someone dies, their assets receive a "step-up" in basis to the current fair market value at the date of death. The beneficiary who inherits the asset can then sell it immediately with zero capital gains tax.

In most states, this step-up applies only to the deceased spouse's share of jointly held property. If a couple bought a house for $100,000 and it's worth $500,000 when one spouse dies:

• Common law states (normal rule): Only the deceased spouse's half gets a step-up. The surviving spouse's basis becomes $300,000 (half the original $100,000 plus half the current $500,000). Selling for $500,000 triggers a $200,000 taxable gain.
• Community property states: Both halves get a step-up. The surviving spouse's basis becomes the full $500,000. Selling immediately triggers zero capital gains tax.

That difference — $200,000 in taxable gains — translates to roughly $30,000 to $47,000 in federal and state capital gains taxes that simply disappear with community property treatment.

How South Dakota's Special Spousal Trust Works

Under SDCL Chapter 55-17, married couples can create a "Special Spousal Trust" that treats their assets as community property for federal tax purposes. This trust invokes IRC Section 1014(b)(6), which grants the full step-up in basis to both spouses' shares when either spouse dies.

The basic structure:

1. Both spouses create the trust together and transfer assets into it
2. The trust document specifically classifies the property as community property under SDCL 55-17
3. Both spouses retain full use and control of the assets during their lifetimes
4. When one spouse dies, all trust assets receive a step-up to current fair market value — not just the deceased spouse's half

The trust can be revocable, meaning either spouse can terminate it at any time. This is not a permanent, irrevocable commitment — it's a structural classification that produces a significant tax benefit.

Who Benefits Most

The value scales with appreciated assets. Families with the largest potential benefit typically include:

• Long-held real estate: A family home purchased decades ago for a fraction of its current value
• Agricultural land: South Dakota farmland that has appreciated from $500 per acre to $3,000+ per acre over a generation
• Investment portfolios: Stocks and funds with decades of unrealized gains
• Business interests: Ownership in a family business that has grown substantially in value

For a couple with $2 million in combined appreciated assets and a cost basis of $400,000, the community property treatment eliminates roughly $1.6 million in potential capital gains at the first spouse's death. At a 23.8% combined federal rate (20% long-term capital gains plus 3.8% net investment income tax), that's approximately $380,000 in tax savings.

Requirements and Limitations

The Special Spousal Trust is a legal document that must comply with SDCL Chapter 55-17's specific requirements:

• Both spouses must consent to community property treatment
• The trust must explicitly state that the property is community property
• At least one trustee must be a "qualified person" — a South Dakota resident or South Dakota-chartered trust company
• The trust applies to property classified into it; not all marital property becomes community property automatically

This is not a DIY project. The interaction between South Dakota trust law, federal income tax rules, and potential estate tax implications requires professional structuring — typically an estate planning attorney working with a CPA.

The Broader Estate Planning Picture

The community property trust is an advanced tool that makes sense for families with significant unrealized capital gains. For most South Dakota families with more modest estates, the foundational planning tools — a valid will, transfer on death deeds, coordinated beneficiary designations, and powers of attorney — are the priority.

Getting those basics right is what the South Dakota Basic Estate Planning Kit covers. If your estate eventually grows to the point where a community property trust makes financial sense, having the foundational documents already in order means the attorney engagement focuses on optimization rather than starting from scratch.

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