The Intestacy Gap: 9.6 Million Unmarried Couples and 2.3 Million Stepkids the Law Leaves Out

Disclaimer: General educational research only — not legal, tax or financial advice. Figures are estimates with the limits explained in the methodology. Verify with official sources and a qualified professional before making decisions.

Estate Planning Data & Research → The Intestacy Gap: 9.6 Million Unmarried Couples and 2.3 Million Stepkids the Law Leaves Out

Every state has a default plan for people who die without a will. It’s called intestate succession, and it’s built around one kind of family: a married couple and their biological or adopted children.

That plan doesn’t fit a lot of households anymore. Census Bureau data shows 9.6 million households are headed by an unmarried couple, and 2.3 million children under 18 are stepchildren of the person who heads their home. In most states, neither the live-in partner nor the stepchild inherits anything when there’s no will.

We pulled the latest Census numbers for all 50 states and D.C. and checked each state’s inheritance law for two questions: does an unmarried partner ever get a share, and can a stepchild ever inherit?

If you live with a partner or are raising stepkids, a will is the only reliable way to make sure they’re included. See whether you need a will, a living trust or both.

Key findings

• 9,593,464 U.S. households (±58,633) are cohabiting couples. That’s 7.2% of all households (±0.04 points). There are about 15.5 cohabiting-couple households for every 100 married-couple households. About 551,000 of the cohabiting couples are same-sex couples.
• Vermont has the highest share of cohabiting-couple households at 11.2% (±1.0). That’s statistically higher than any other state, including Maine (9.5%) and Oregon (9.1%). Mississippi (4.9%) and Alabama (5.0%) have the lowest shares and are statistically tied with each other.
• The biggest totals are in the biggest states: California has about 1.08 million cohabiting-couple households, Texas 735,000, and Florida 692,000.
• 2,290,739 children under 18 (±38,519) live with a stepparent who heads the household. That’s 3.2% of kids in households. Counting adults, the householder has 3.8 million stepchildren, including 1.5 million aged 18 or older. Grown stepchildren are just as cut out of intestacy as young ones.
• West Virginia has the highest stepchild share (5.4% ±1.0), but it’s statistically tied with Wyoming, Kentucky and Oklahoma. D.C. (1.0%) and New York (1.9%) are lowest.
• None of the 51 statutes we checked gives a live-in partner a share just for living together. The partner has to be a legal spouse or hold a registered status the state treats like marriage (California, D.C., Maine, Nevada, New Jersey and Oregon domestic partners; Illinois and New Jersey civil unions; Hawaii reciprocal beneficiaries; and a few others). New Hampshire has an unusual exception: a couple who lived together as spouses for three years until one died is “deemed to have been legally married” (RSA 457:39).
• Stepchildren get in only as a last resort, if at all. We found 16 states where stepchildren, or a late spouse’s family, can inherit when no blood relative exists. Before that point, the estate goes to parents, siblings, nieces, nephews and cousins. In 33 jurisdictions, unadopted stepchildren never inherit, and the estate escheats (goes to the state) before they’d get anything. Wyoming’s statute says it outright.

Who inherits when there’s no will

The rule of thumb is simple. Marriage and adoption count. Living together and raising someone’s child don’t.

If you die without a will and you’re not married to your partner, your state’s intestacy law usually skips your partner entirely. It typically sends your property to your children. If you have none, it goes to your parents, then your siblings, and so on down the family tree. Your partner might have to move out of a house you owned, even after decades together.

Stepchildren are in the same spot. A stepchild you raised from age 3 isn’t your “child” under intestacy law unless you adopted them. Colorado and Tennessee spell it out: their probate codes define “child” to exclude “a person who is only a stepchild.”

States where stepchildren can be last-resort heirs

These states let stepchildren, or a deceased spouse’s family, inherit when nobody closer is left. In practice that means no living parents, siblings, nieces, nephews, grandparents, aunts, uncles or cousins:

• Stepchildren named directly: Connecticut, Kentucky (new as of July 15, 2026), Maryland, New Jersey, Ohio
• A deceased spouse’s descendants or relatives: Arkansas, Florida, Hawaii, Iowa, Kansas, Maine, Missouri, New Mexico, North Dakota, Utah, Virginia
• Narrow versions: California (issue of a predeceased spouse; a stepchild can also count as a child if a legal barrier blocked an adoption that was intended from childhood), Washington (only for property that came from the stepparent’s late spouse)

Partners: the few routes to a spouse’s share

In D.C., Iowa, Oklahoma and Rhode Island the rule comes from court decisions, not a statute. Rhode Island’s courts want “clear and convincing” proof. We couldn’t pull that state’s court opinion from the judiciary’s own website, so we read it in a published secondary copy. Utah’s version needs a court or agency order, and the petition has to be filed within a year after the relationship ends. We also couldn’t load the official text of Utah’s 2026 change, so treat that end date as reported, not confirmed.

Common-law marriage isn’t a shortcut. You generally have to prove you both agreed to be married and presented yourselves as married. Living together isn’t enough, and many states abolished it decades ago: Florida in 1968, Ohio in 1991, Idaho in 1996, Georgia in 1997 and Pennsylvania in 2005.

Full state table

Cohabiting-couple households and stepchildren are ACS 2024 1-year estimates with 90% margins of error. Legal columns are summaries; the CSV has citations and links.

Every row was checked against an official source; the confidence code for each rule is in the CSV. “Spouse only” means we found no partner status in the state’s intestacy statute (from Family Estate Guide’s earlier 51-jurisdiction read of those statutes); it doesn’t rule out a common-law marriage claim.

What this means for your family

• If you live with a partner and own anything together, the deed matters as much as the will. A house titled “joint tenants with right of survivorship” goes to the survivor no matter what. A house in one name goes through probate to that person’s legal heirs. Our guide to avoiding probate covers the options.
• If you’re raising stepchildren, a will (or adoption) is the only reliable way to include them. In most states the law would pass them over for a cousin you’ve never met.
• Beneficiary forms still beat everything. Life insurance, retirement accounts and payable-on-death accounts go to whoever is named on the form, married or not. See Money that skips the will.
• A trust can handle blended families more precisely than a will. For example, it can let a partner stay in the house for life and then pass it to your children. Compare the two in trust vs. will.

This page covers dying without a will. For what a surviving spouse can claim against a will, see elective share by state.

Related research: same-sex couples, married vs. unmarried, by state shows how many couples live together without being married, which matters when there is no will.

Methodology

Data. U.S. Census Bureau, American Community Survey (ACS) 2024 1-year estimates, released September 2025. These were pulled from the Census Data API for all states, D.C. and the U.S. Puerto Rico isn’t included.

• Households by type: table B11009 (Unmarried-partner households by sex of partner). B11009_001 = all households, B11009_002 = married-couple households, B11009_007 = cohabiting-couple households, and B11009_008/009 = opposite-sex/same-sex.
• Stepchildren under 18: table B09018 (Relationship to householder for children under 18 in households). B09018_001 = all children under 18 in households; B09018_005 = stepchild.
• Stepchildren of all ages: table B09019 (Household type by relationship). B09019_017 = stepchild of the householder, any age.
• API call (key omitted): https://api.census.gov/data/2024/acs/acs1?get=NAME,B11009_001E,B11009_001M,B11009_002E,B11009_007E,B11009_007M,B11009_008E,B11009_009E,B09018_001E,B09018_005E,B09018_005M,B09019_017E&for=state:* (and for=us:1)

Margins of error. Shares use the Census Bureau’s formula for the MOE of a proportion. All MOEs are at the 90% confidence level. We call two states different only when the gap between them is bigger than the combined margin of error (z > 1.645); otherwise we call them statistically tied.

Limits. “Stepchild” here means a stepchild of the householder, the person in whose name the home is owned or rented. Stepchildren of other adults in the home aren’t counted, so the real number is higher. “Cohabiting couple” means the householder lives with an unmarried partner. Couples where neither partner is the householder aren’t counted.

Legal research. We read each state’s intestate succession statute for stepchild and last-resort provisions, and checked partner statuses (domestic partnership, civil union, common-law marriage) in the marriage and probate codes. Statutes were checked October 6, 2026. Confidence codes:

• A: official statute text from the legislature’s website, archived with a checksum.
• B: official source read indirectly, or an older official code release.
• C: we couldn’t read it on an official site. The rule text in the CSV says so in plain English (only Rhode Island’s common-law marriage case on this page).

Georgia, Mississippi and Tennessee stepchild rules were read in the states’ official code releases through a public mirror (code B), because those states publish their codes only through a vendor site. Oklahoma’s rule comes from the Oklahoma Senate’s official statute compilation. Common-law marriage was checked against statutes, an Iowa administrative rule and official court opinions (Oklahoma’s OSCN and the D.C. Court of Appeals). Rhode Island’s rests on a secondary copy of Luis v. Gaugler (R.I. 2018). Utah’s 2026 change is reported but not confirmed.

This is general information, not legal advice. Laws change; check your state’s current statute or ask a local attorney.

Sources

• U.S. Census Bureau, ACS 2024 1-year, tables B11009, B09018, B09019: https://data.census.gov/ and https://api.census.gov/data/2024/acs/acs1
• Census Bureau, ACS margin-of-error guidance (Understanding and Using ACS Data, ch. 8): https://www.census.gov/programs-surveys/acs/library/handbooks/general.html
• State statutes: one link per state in the CSV download. Key examples:
  • Conn. Gen. Stat. 45a-439: https://www.cga.ct.gov/current/pub/chap_802b.htm
  • Ohio Rev. Code 2105.06: https://codes.ohio.gov/ohio-revised-code/section-2105.06
  • Va. Code 64.2-200: https://law.lis.virginia.gov/vacode/title64.2/chapter2/section64.2-200/
  • Wyo. Stat. 2-4-101: https://wyoleg.gov/statutes/compress/title02.pdf
  • N.H. RSA 457:39: https://gc.nh.gov/rsa/html/XLIII/457/457-39.htm
  • Cal. Fam. Code 297.5: https://leginfo.legislature.ca.gov/faces/codes_displaySection.xhtml?lawCode=FAM&sectionNum=297.5

Related research: will contest watch looks at the other side, what happens when a will exists but is challenged in court.

FAQ

Does my unmarried partner inherit if I die without a will?

In almost every state, no. Intestacy laws give shares to a “surviving spouse” and blood or adopted relatives. A partner only qualifies through a registered domestic partnership or civil union the state recognizes, a valid common-law marriage, or New Hampshire’s deemed-marriage rule.

Do stepchildren inherit from a stepparent without a will?

Usually not, unless the stepparent adopted them. About 16 states let stepchildren or a late spouse’s family inherit, but only when no blood relatives are left. That’s rare.

Can a stepchild inherit if the stepparent always intended to adopt?

In California, a stepchild can be treated as a child if the relationship began when the child was a minor, continued for life, and a legal barrier blocked an adoption the stepparent would have completed (Prob. Code 6454). The proof standard is “clear and convincing evidence.”

If we’ve lived together for years, aren’t we common-law married?

Probably not. Only a minority of states still allow new common-law marriages, and they require an agreement to be married and holding yourselves out as married, not just time together.

What’s the simplest fix?

A will that names your partner and stepchildren. Also add them as beneficiaries on accounts and insurance, or title the house so it passes directly. A revocable living trust can do all of this in one place.

Cite this data

Published October 6, 2026 by Family Estate Guide. Data vintage: ACS 2024 1-year estimates (released September 2025). Statutes checked October 6, 2026. Editorial standards.