Community Property Step-Up Calculator

The primary difference in how assets are treated for tax purposes after a spouse's death comes down to your state's marital property laws. The United States has two systems: community property and common law. This distinction has a massive impact on the cost basis of assets for the surviving spouse.

Cost basis is, simply, the original value of an asset for tax purposes, usually the purchase price. When you sell an asset, you pay capital gains tax on the difference between the sale price and the cost basis. A "step-up in basis" adjusts this original cost to the asset's fair market value (FMV) on the date of death, reducing or eliminating the taxable gain.

Here’s how the two systems differ:

This "double step-up" is a unique advantage for residents of community property states, providing a clean slate for the surviving spouse and allowing for tax-free liquidation or diversification of appreciated assets.

The financial benefit of the community property step-up can be immense. Let's walk through a realistic scenario to see the dollar-for-dollar impact.

Scenario:

• A married couple in California (a community property state) bought a rental property 25 years ago for $400,000.
• Today, one spouse passes away, and the property's fair market value is $1,200,000.
• The unrealized capital gain is $800,000 ($1.2M FMV - $400k basis).
• The surviving spouse decides to sell the property to simplify their finances.

Outcome in California (Community Property):

1. Basis Step-Up: Both halves of the property are stepped up to the current market value. The new basis is $1,200,000.
2. Sale: The property is sold for $1,200,000.
3. Taxable Gain: $1,200,000 (Sale Price) - $1,200,000 (New Basis) = $0.
4. Capital Gains Tax Owed: $0.

Now, let's imagine the same couple lived in Colorado (a common law state).

Outcome in Colorado (Common Law):

1. Basis Step-Up: Only the deceased spouse's 50% share gets a step-up.
   • Survivor's half of original basis: $400,000 / 2 = $200,000.
   • Deceased's half stepped up to FMV: $1,200,000 / 2 = $600,000.
   • The new total basis is $200,000 + $600,000 = $800,000.
2. Sale: The property is sold for $1,200,000.
3. Taxable Gain: $1,200,000 (Sale Price) - $800,000 (New Basis) = $400,000.
4. Capital Gains Tax Owed: Assuming a 15% federal rate, a 4.4% state rate, and the 3.8% NIIT, the total tax rate is 23.2%. The tax bill would be $400,000 * 23.2% = $92,800.

In this example, living in a community property state saves the surviving spouse nearly $93,000 in taxes, freeing up that capital for their retirement income needs.

The calculator determines your potential tax savings by computing the capital gains tax owed under three scenarios: no step-up, a half step-up (common law), and a full step-up (community property). The core formulas focus on establishing the new basis and the resulting taxable gain.

The new basis for a surviving spouse in a common law state is calculated as:

Half Step-Up Basis = (Original Cost Basis / 2) + (Fair Market Value at Death / 2)

The taxable gain is then found by subtracting this new basis from the sale price:

Taxable Gain (Common Law) = Sale Amount - Half Step-Up Basis

Finally, the total tax savings from living in a community property state is the difference between the tax owed in a common law state and the tax owed in a community property state (which is typically zero if the asset is sold immediately).

Extra Savings From Community Property = Tax Owed (Common Law) - Tax Owed (Community Property)

Where:

• Original Cost Basis = The initial purchase price of the asset plus any capital improvements.
• Fair Market Value at Death = The market value of the asset on the date the first spouse passes away.
• Sale Amount = The price at which the asset is sold by the surviving spouse.
• Tax Owed = The taxable gain multiplied by your combined federal and state capital gains tax rates.

Understanding these mechanics is key to appreciating the value of proper asset titling and estate planning, especially for couples with long-held, highly appreciated assets.

The step-up in basis applies to most capital assets that have appreciated in value. However, for the full step-up in community property states, the asset must be correctly identified and titled as "community property."

Assets that typically qualify include:

• Real Estate: Primary residences, vacation homes, and investment properties.
• Taxable Brokerage Accounts: Stocks, bonds, and mutual funds held outside of retirement accounts.
• Business Interests: Ownership stakes in a privately held company.
• Art, Antiques, and Collectibles.

Crucial Point on Titling: To receive the full step-up, the property must be legally considered community property. Titling assets as "Joint Tenants with Right of Survivorship" (JTWROS) can sometimes jeopardize the full step-up in certain states, as it might be treated as separate property. Spouses should consult an estate planning attorney to ensure their deeds and account registrations reflect their intent.

Assets that DO NOT get a step-up in basis: The step-up rule does not apply to assets classified as "Income in Respect of a Decedent" (IRD). These are assets that would have been taxable as ordinary income to the decedent had they lived.

The most common examples include:

• Traditional IRAs, 401(k)s, and 403(b)s: Beneficiaries inherit the pre-tax nature of these accounts and will owe ordinary income tax on withdrawals. Use an IRA calculator to project future values and tax liabilities.
• Pensions and Annuities: Payments from a defined benefit pension plan are taxable income to the beneficiary.
• Deferred Compensation and Uncollected Salary.

Beneficiaries of these accounts must still follow the rules for inherited retirement plans, including taking Required Minimum Distributions (RMDs).

While the full step-up is a powerful default rule, proactive planning can ensure you maximize its benefit.

1. Verify Asset Titling: This is the most critical step. Work with an estate planning attorney to review deeds, brokerage accounts, and other assets. Ensure they are explicitly titled as "community property" rather than JTWROS or "tenants in common" to avoid any ambiguity.
2. Consider a Transmutation Agreement: If one spouse brought significant separate property (e.g., an inheritance or assets owned before marriage) into the marriage, you might consider a "transmutation agreement." This legal document can reclassify separate property as community property, making it eligible for the full step-up. This has significant legal consequences for divorce, so it requires careful consideration.
3. Explore Community Property Trusts: For couples in common law states, a special type of trust may offer a solution. States like Alaska, Tennessee, South Dakota, Kentucky, and Florida allow couples to create a "community property trust," which can hold assets and potentially qualify them for the 100% step-up. This is a complex strategy that requires specialized legal advice.
4. Plan the Timing of a Sale: The step-up resets your basis to the value at the date of death. Any appreciation that occurs after that date is a new capital gain. For a surviving spouse who plans to sell an asset, doing so relatively soon after the death can lock in the maximum tax benefit before new gains accrue. This can be a key part of managing a retirement withdrawal strategy.

To get the most accurate estimate, you'll need a few key pieces of information. The calculator's inputs are grouped into three main categories:

• Property Details: This includes the Total Community Property Value (its current fair market value), the Original Cost Basis (what you paid for it, plus improvements), and the State you live in. Selecting a community property state versus a common law state is the primary driver of the calculation.
• Tax Rates & Filing: You will need your estimated Federal and State Capital Gains Rates. For many retirees, the federal rate is 15% or 20%. You should also indicate if the Net Investment Income Tax (NIIT) of 3.8% applies, which it often does on large gains.
• Sale & Growth Assumptions: The calculator asks for the Planned Sale Amount (what percentage of the asset you plan to sell) and the Years Until Expected Sale. Selling immediately after the step-up maximizes the benefit, while waiting allows new, taxable gains to accumulate.

What is a step-up in basis at death?

A step-up in basis is a tax provision that adjusts the cost basis of an inherited asset to its fair market value on the date of the original owner's death. This reduces or even eliminates the capital gains tax the beneficiary would owe if they sell the asset.

Which states are community property states?

There are nine community property states: Arizona, California, Idaho, Louisiana, Nevada, New Mexico, Texas, Washington, and Wisconsin. Alaska, South Dakota, Tennessee, Kentucky, and Florida are common law states that allow couples to opt into a community property system via a special trust.

Is a full step-up always better than a half step-up?

From a purely capital gains tax perspective, a full step-up is always better than a half step-up because it results in a higher cost basis for the surviving spouse, leading to a smaller taxable gain upon sale.

Do I still have to pay estate tax with a step-up in basis?

Yes, the two are separate taxes. The step-up in basis relates to capital gains income tax for the beneficiary. The estate tax is a tax on the decedent's total estate value if it exceeds the federal exemption (~$13.99 million in 2026). An estate can be large enough to owe estate tax while its assets still receive a step-up in basis. Use an estate tax calculator to see if this applies to you.

Do retirement accounts like a 401(k) or Roth IRA get a step-up in basis?

No. Retirement accounts are considered "Income in Respect of a Decedent" (IRD) and do not receive a step-up in basis. Beneficiaries of traditional (pre-tax) accounts like a 401(k) or IRA will owe ordinary income tax on withdrawals, just as the original owner would have.

What happens if we move from a common law state to a community property state?

The character of property is generally determined by the laws of the state where the couple resided when the asset was acquired. Property acquired in a common law state and brought into a community property state may be treated as "quasi-community property," which often qualifies for the full step-up. This is a complex area of law requiring professional advice.

Can we get the full step-up benefit if we live in a common law state?

Generally, no. However, a few common law states (Alaska, Tennessee, South Dakota, Kentucky, Florida) allow couples to create a Community Property Trust. By transferring assets into this specialized trust, residents of those states may be able to achieve the same full step-up benefit.

How does the step-up affect Required Minimum Distributions (RMDs)?

The step-up in basis does not affect RMDs. RMDs apply to pre-tax retirement accounts, which are not eligible for a step-up. The tax treatment and distribution rules for inherited IRAs and 401(k)s are separate from the rules for capital assets. See our guide on how to reduce taxes on Required Minimum Distributions for more information.

Understanding the step-up in basis is a crucial part of retirement and legacy planning. After seeing your potential savings, consider these next steps:

1. Estimate Your Estate's Value: Use the Estate Tax Calculator to determine if your assets are near the federal exemption threshold.
2. Model Your Survivor's Finances: For a surviving spouse, a large, tax-free cash infusion from selling a stepped-up asset changes the financial picture. Use the How Long Will My Money Last Calculator to model how these new funds can support long-term spending.
3. Review Your Withdrawal Plan: Selling an asset creates a lump sum that needs to be managed. A Retirement Withdrawal Calculator can help you determine a sustainable withdrawal rate from a newly diversified portfolio.

Last updated: July 2026