Conjugal property is the civil-law term for what most U.S. jurisdictions call community property: a system that treats nearly everything a married couple earns or acquires during the marriage as owned equally by both spouses, regardless of whose name is on the paycheck, the title, or the account. Nine states apply this rule by default — Arizona, California, Idaho, Louisiana, Nevada, New Mexico, Texas, Washington, and Wisconsin. Three more — Alaska, Tennessee, and South Dakota — let couples opt in through a written agreement or special trust. Everywhere else, the equitable distribution system applies instead, dividing marital property fairly but not necessarily in half.
The practical consequences show up in three places: what you own during the marriage, how property gets split if the marriage ends, and what the IRS expects on your tax return.
What Counts as Community Property
The default rule is simple. Anything acquired during the marriage through either spouse’s effort or earnings goes into the shared pool. Wages, bonuses, commissions, and self-employment profits all qualify no matter whose name is on the check. Houses, cars, and furniture bought with those earnings are community property too.1Internal Revenue Service. Publication 555 (12/2024), Community Property
Investment returns follow the same principle. Dividends from stocks bought during the marriage, interest on jointly funded savings, and rent from property purchased with marital earnings all belong to the community estate. Contributions to a brokerage account, mutual fund, or business during the marriage create community assets even if only one spouse managed the money.
Four states push the rule further. In Idaho, Louisiana, Texas, and Wisconsin, income generated by separate property — rent from a building one spouse owned before the wedding, for example — is typically community income as well.1Internal Revenue Service. Publication 555 (12/2024), Community Property
What Stays Separate
Not everything a married person touches becomes shared. Assets owned before the marriage remain separate. Gifts and inheritances received by one spouse during the marriage stay with that spouse alone. If your grandmother leaves you a house or your parents hand you $50,000, that belongs to you, not to the marital community. Personal injury settlements are often separate too, though states differ on whether the portion compensating for lost wages gets treated the same as the portion covering pain and suffering.
Property bought with clearly separate funds also keeps its separate character. Sell your pre-marital car, use the proceeds for a new one, and the new car is still yours — as long as you can trace the money back to the original asset. “Trace” is the operative word. Without a clean paper trail, the presumption that anything acquired during marriage is community property takes over, and the burden shifts to you to prove otherwise.
How Separate Property Quietly Becomes Shared
This is where most couples create problems without meaning to. Commingling — mixing separate funds with community funds — is the fastest way to lose the separate character of an asset. Deposit an inheritance into a joint checking account that both spouses use for groceries and bills, and those dollars become effectively impossible to untangle. When a court can’t tell which money came from where, the entire account usually gets treated as community property.
Transmutation is the more deliberate cousin. Adding your spouse’s name to the title of a pre-marital home can convert that separate asset into community property. Using community funds to pay the mortgage on a separate property can give the community an ownership interest in the asset proportional to the payments made. The safest practice is to keep separate accounts funded only with separate money, avoid using marital earnings to maintain pre-marital assets, and document significant transactions as you go.
Shared Debts
Community property isn’t just about assets. Debts incurred for the benefit of the family during the marriage are generally shared obligations. Mortgages, car loans, medical bills, credit card charges for household expenses, and costs of raising children all fall into the community debt category.
The line between community and separate debt turns on purpose and timing. A student loan one spouse took out before the wedding is typically that spouse’s separate obligation. A gambling debt or luxury purchase that gave the family nothing may also be classified as separate, leaving only the spending spouse on the hook. The line gets blurry fast. A credit card used 80% for groceries and 20% for personal hobbies creates exactly the kind of commingling problem that makes divorce litigation expensive.
Creditors generally can reach community assets to satisfy debts either spouse incurred for the family’s benefit. One spouse’s separate property is usually shielded from the other spouse’s separate debts, though the specifics vary by state.
Retirement Accounts and the Federal Overlay
Retirement accounts are often the biggest asset in a marriage, and federal law overrides state community property rules in important ways. Employer-sponsored plans like 401(k)s and pensions are governed by ERISA, which creates its own set of spousal protections.
Under ERISA, a pension or 401(k) must generally name the participant’s spouse as beneficiary. If the participant wants to name someone else, the spouse must consent in writing. This protection exists regardless of what state community property law would otherwise say.
Dividing a retirement account at divorce requires a Qualified Domestic Relations Order, or QDRO. The order tells the plan administrator to pay a specified portion of the participant’s benefits to the other spouse. A QDRO must identify both spouses by name and address, specify the amount or percentage, and stay within the benefits the plan actually offers. It can’t create benefits the plan doesn’t provide.2Internal Revenue Service. Retirement Topics – QDRO Qualified Domestic Relations Order
One wrinkle matters at death. If the non-participant spouse dies first, the Supreme Court has held that ERISA preempts state community property law, so the non-participant cannot pass their community property interest in the plan to their heirs by will. The interest effectively reverts to the participant spouse.3Justia US Supreme Court. Boggs v. Boggs, 520 U.S. 833 (1997)
IRAs are different. They aren’t covered by ERISA, so state community property rules apply in full. Contributions made with community earnings create community property, and the non-account-holder spouse has a claim to their share. For federal tax purposes, however, IRA distributions are taxable to the spouse whose name is on the account regardless of community property status.1Internal Revenue Service. Publication 555 (12/2024), Community Property
Federal Tax Consequences
Splitting Income on Separate Returns
If you live in a community property state and file a separate federal return from your spouse, you must report exactly half of all community income plus all of your own separate income. That covers wages, self-employment earnings, dividends, interest, and rental income from community assets. Both spouses must attach Form 8958 to their separate returns showing how the income was allocated.4Internal Revenue Service. About Form 8958, Allocation of Tax Amounts Between Certain Individuals in Community Property States
The splitting rule can help or hurt. When one spouse earns far more than the other, filing separately with community allocation can shift income to the lower-earning spouse’s return. But filing separately also disqualifies you from several credits and deductions, so the math isn’t automatic.
The Double Step-Up in Basis
The biggest tax advantage shows up at death. When one spouse dies, the surviving spouse’s half of the community property — not just the deceased spouse’s half — gets its tax basis reset to fair market value as of the date of death.5Office of the Law Revision Counsel. 26 USC 1014 – Basis of Property Acquired From a Decedent
Consider a couple who bought stock for $100,000 that’s worth $500,000 when one spouse dies. In a separate property state, only the deceased spouse’s half gets the step-up; the survivor’s half keeps the original $50,000 basis, meaning a sale would trigger $200,000 in taxable gains on that half. In a community property state, the full $500,000 gets the new basis. If the surviving spouse sells the next day, the capital gains tax is zero. For couples with highly appreciated real estate or investment portfolios, the difference can run into six figures.
Transfers at Divorce
Dividing community property in a divorce triggers no federal income tax between spouses. The IRS treats these transfers as gifts, and the receiving spouse takes over the transferring spouse’s original tax basis. The rule applies to any transfer that happens within one year after the marriage ends or that’s related to the divorce.6Office of the Law Revision Counsel. 26 USC 1041 – Transfers of Property Between Spouses or Incident to Divorce
No tax now doesn’t mean no tax ever. Because the receiving spouse inherits the original basis, any built-in gain travels with the asset. Receive stock in the divorce with a basis of $10,000 and a market value of $80,000, and you’ll owe capital gains tax on $70,000 when you sell. That makes it important to compare the after-tax value of assets during negotiations, not just the face value. A $100,000 brokerage account with a $20,000 basis is worth considerably less than $100,000 in cash.
Changing the Rules by Agreement
None of this is set in stone. A prenuptial agreement signed before the wedding, or a postnuptial agreement signed during the marriage, can override the default rules. Couples can designate specific assets as separate, define how future earnings will be classified, or opt out of community property treatment entirely.
For an agreement to hold up, most states require that both parties sign voluntarily with a reasonable understanding of what they’re giving up. Full financial disclosure is essential. An agreement signed under pressure, without time to review, or where one spouse concealed significant assets or debts is vulnerable to being thrown out. Most states also bar prenuptial agreements from limiting child support obligations.
Couples who move between community property and equitable distribution states should have the agreement reviewed under the new state’s rules, since what’s enforceable in one may not be in another.
Dividing Community Property at Divorce
When a marriage ends, the community estate has to be inventoried, valued, and divided. Both spouses disclose every asset and liability — bank accounts, real estate, vehicles, retirement accounts, business interests, and debts. Courts generally start from a presumption of equal division, awarding each spouse half the net community estate after debts are paid.
The family home is usually the hardest piece. The common resolution is a buyout: one spouse keeps the house and compensates the other for their share of the equity, with equity calculated as current appraised value minus the remaining mortgage. The spouse keeping the house typically refinances the loan into their own name. Until that refinance closes, both spouses stay liable on the original mortgage no matter what the divorce decree says — a detail that catches many people off guard.
Retirement accounts require a QDRO, and the process can take months if the plan administrator asks for revisions. Business interests may need a professional valuation. Liquid accounts are simpler to split but still require attention to the tax basis of any transferred investments.
Hiding or wasting community assets during a divorce — sometimes called dissipation — has real consequences. Courts can treat the missing assets as if they still existed when dividing the estate, effectively charging the offending spouse’s share for the lost value. In severe cases, that spouse may face contempt sanctions.
What Happens When a Spouse Dies
At death, the community estate splits differently than in divorce. The surviving spouse automatically keeps their own half of the community property. That half was always theirs and doesn’t pass through probate. The deceased spouse’s half passes according to their will, or under the state’s intestacy laws if no will exists.
This means a spouse in a community property state cannot entirely disinherit the other through a will, because the surviving spouse’s half was never the deceased’s to give away. The deceased can direct only their own half. Combined with the full step-up in basis, this gives surviving spouses in community property states both stronger ownership protections and more favorable tax treatment than those in equitable distribution states.5Office of the Law Revision Counsel. 26 USC 1014 – Basis of Property Acquired From a Decedent
Creditors of the deceased must be satisfied from the deceased’s half of the community estate and any separate property before the remainder passes to heirs. The surviving spouse’s half is generally protected from the deceased’s individual creditors, though debts that were community obligations during the marriage may still reach community assets depending on state law.