Yes, second cousin marriage is legal in all 50 states. No state’s incest or marriage statutes reach second cousins, who share only a set of great-grandparents and roughly 3.13 percent of their DNA. A second cousin marriage is treated exactly like any other marriage for every legal purpose: taxes, inheritance, immigration, and spousal rights all apply the same way.
Why No State Prohibits It
State marriage laws prohibit unions between close relatives: siblings, parents and children, aunts or uncles with nieces or nephews, and in more than 30 states, first cousins. Second cousins fall outside every one of these lists.
Family law uses the civil law method to measure how closely two people are related. You count the steps from one person up to the shared ancestor and then back down to the other person. Siblings are second-degree relatives. First cousins, who share grandparents, are fourth-degree. Second cousins, who share great-grandparents, are sixth-degree. Most states draw the prohibition line at or below the fourth degree, so a sixth-degree relationship sits well outside the restricted zone.
Because the marriage is valid, it carries the full package of spousal rights. You can file a joint federal income tax return.1Office of the Law Revision Counsel. 26 USC 6013 – Joint Returns of Income Tax by Husband and Wife You inherit under state intestacy laws if your spouse dies without a will. Criminal incest statutes, which carry felony penalties in nearly every state and prison terms running from under two years to 20 depending on the jurisdiction and relationship, do not apply to second cousins.
Make Sure You’re Actually Second Cousins
People often mix up “second cousin” with “first cousin once removed,” and the confusion causes unnecessary worry about whether a marriage is allowed. The quickest way to check which relationship you have is to ask what ancestor you share.
- If you share grandparents, you are first cousins. This is a fourth-degree relationship, and many states restrict it.
- If one of you is the child of the other’s first cousin, you are first cousins once removed. You share grandparents but sit a generation apart. State laws vary on this relationship.
- If you share great-grandparents and belong to the same generation, you are second cousins. This is a sixth-degree relationship, and it is legal everywhere.
The “removed” label always signals a generational gap rather than a greater or lesser degree of closeness. A first cousin once removed actually shares more DNA with you than a second cousin does. If your parents are first cousins to each other, you and the other person’s child are second cousins.
Getting the Marriage License
The licensing process is the same one every couple goes through. There is no special form for second cousins, no additional approval, and no disclosure requirement beyond the standard application questions.
Both parties typically appear in person at the local clerk’s office with valid government-issued photo identification. A Social Security number is required in most jurisdictions. The application asks for basic information about each party’s parents, which is how clerks screen for prohibited relationships. Answering honestly is not a problem; your relationship is not within any state’s restricted degrees.
No state currently requires a blood test or medical exam before issuing the license. The usual minimum age to marry without parental consent is 18, with state-by-state variation on exceptions. License fees generally run from about $20 to $120 depending on the county, and roughly a third of states impose a waiting period of one to three days between applying and using the license. Once issued, the license is valid for a window of about 60 to 180 days, depending on the state. If it expires before the ceremony, you reapply and pay again.
The ceremony must be performed by a legally authorized officiant: a judge, a justice of the peace, an authorized religious leader, and in some states a mayor or county clerk. A few states also recognize self-uniting marriages signed by the couple and witnesses. The officiant signs the completed license and returns it to the clerk’s office within the deadline the state sets, usually 10 days and in some places up to 30.
Recognition If You Move or Immigrate
Because every state permits second cousin marriage, you never need to worry about your marriage losing its validity when you cross a state line. This is a real contrast with first cousin marriages, which can be valid in one state and void in another that bans them.
For immigration, USCIS generally recognizes a marriage as valid if it was legally performed where the ceremony took place.2U.S. Citizenship and Immigration Services. USCIS Policy Manual Volume 6, Part B, Chapter 6 – Spouses When a consular officer suspects a spousal visa petition involves blood relatives, the officer can request an advisory opinion from the Office of Legal Affairs.3U.S. Department of State Foreign Affairs Manual. 9 FAM 102.8 Family-Based Relationships In practice, that scrutiny is aimed at closer relationships like first cousins, uncle-niece, or sibling marriages. A second cousin marriage legally performed anywhere is unlikely to draw additional review, but if you are sponsoring a spouse through Form I-130, expect to document the marriage the same way any other petitioner would: a certified marriage certificate, evidence of a shared life, and proof that any prior marriages were legally ended.4U.S. Citizenship and Immigration Services. Instructions for Form I-130, Petition for Alien Relative
Genetic Risk and Carrier Screening
The baseline risk of any baby being born with a significant birth defect or disability is about 2 to 3 percent in the general population. For second cousins, that number rises to roughly 3.5 percent. The increase is real but modest in absolute terms: more than 96 out of 100 babies born to second cousin parents will not have a major genetic condition.
The added risk comes from autosomal recessive conditions, where both parents carry a silent copy of the same gene variant. Because second cousins inherit some DNA from the same great-grandparents, their chance of both carrying the same recessive variant is slightly higher than it would be for two unrelated people. The American College of Obstetricians and Gynecologists defines consanguinity as a union between second cousins or closer and recommends that these couples be offered genetic counseling to discuss the increased risk and the limits of carrier screening.5American College of Obstetricians and Gynecologists. Carrier Screening in the Age of Genomic Medicine
Expanded carrier screening panels can test both partners for hundreds of recessive conditions at once, and some medical guidelines recommend the broadest available tier for consanguineous couples. A genetic counselor can walk you through which tests make sense, interpret the results, and put the actual risk in context. Doing this before conception gives you the most options.
Religious Rules May Still Apply
Civil legality is not the same as religious permission, and if you are planning a religious ceremony, check the denomination’s rules separately.
Under the Catholic Church’s 1983 Code of Canon Law, marriage between blood relatives is invalid up to and including the fourth degree of the collateral line.6The Vatican. Code of Canon Law – Cann. 998-1165 The Church counts degrees the same way civil law does. First cousins land at the fourth degree and need a bishop’s dispensation to marry in the Church. Second cousins, at the sixth degree, fall outside the prohibition and need no dispensation. An older counting method used before 1983 categorized second cousins differently, which still causes confusion in some parishes, but the current Code is clear.
Other traditions vary. Some branches of Islam permit cousin marriage at any level. Hindu customs differ by region and community, with some groups discouraging marriage within the same gotra or clan regardless of the technical degree of relatedness. Talk to your officiant about any denominational requirements that go beyond what civil law demands.