Can You Claim Common Law Marriage on Taxes? State Rules and Filing

You can claim a common law marriage on your federal taxes if that marriage is legally valid in the state where it was formed. When it is, the IRS treats you exactly like a ceremonially married couple: you must file as Married Filing Jointly or Married Filing Separately, and filing as single is not an option. The IRS does not judge your relationship on its own. It defers to state law, and IRS Publication 501 says you are considered married for the whole year if, on December 31, you were “living together in a common law marriage recognized in the state where you now live or in the state where the common law marriage began.”1Internal Revenue Service. Publication 501 – Dependents, Standard Deduction, and Filing Information

Does Your State Recognize Common Law Marriage

Only a limited set of jurisdictions currently allow a couple to form a new common law marriage. If your relationship began in one of them and meets the legal requirements, you have a valid marriage for federal tax purposes.

States That Allow New Common Law Marriages

  • Colorado: both parties must be at least 18, and the marriage cannot be otherwise prohibited by law.
  • Iowa: recognized for purposes of support of dependents and not explicitly prohibited.
  • Kansas: both parties must be 18 or older.
  • Montana: not invalidated by the state’s marriage statutes.
  • Oklahoma: recognized through case law despite a statute requiring a license.
  • Rhode Island: recognized through case law.
  • South Carolina: allows marriages without a valid license.
  • Texas: couples can establish an informal marriage by agreement, cohabitation in Texas, and holding themselves out as married. Texas also lets couples file a Declaration of Informal Marriage with the county clerk.
  • Utah: recognized by statute.
  • District of Columbia: recognized through case law.

New Hampshire is a boundary worth noting. Its statute treats couples who cohabited and were generally known as married for three years as “deemed to have been legally married” only after one partner dies.2New Hampshire General Court. New Hampshire Revised Statutes Section 457-39 That version affects inheritance and survivor benefits. It will not help a living couple file joint tax returns.

Grandfathered Marriages in States That Abolished the Doctrine

Several states no longer allow new common law marriages but still honor unions formed before a cutoff date. If yours was established before the deadline and you have maintained the relationship, it remains valid for federal tax purposes:

What Makes the Marriage Valid

Specific requirements vary by state, but Revenue Ruling 2013-17 identifies three features that common law marriages share: “(1) A present agreement to be married, (2) cohabitation, and (3) public representations of marriage.”5Internal Revenue Service. Revenue Ruling 2013-17 All three must exist together.

A present agreement means both people intend to be spouses right now, not someday. Planning a future wedding does not qualify. Cohabitation means actually living together as a married couple, which is more than sharing an apartment or splitting rent. Public representation means holding yourselves out to others as married, whether by using the same last name, introducing each other as spouses, filing joint documents, or being generally known in your community as a married couple. A couple that lived together for years without agreeing to be married, or that agreed but kept the relationship private, has not formed a common law marriage even in a recognizing state.

Evidence to Keep

If the IRS questions your status, the burden of proof is on you. Useful documentation includes joint bank accounts or credit cards, property held in both names, insurance policies naming each other as spouses, prior returns filed as married, affidavits from people who know you as a married couple, and any declaration or registration of informal marriage filed with a county clerk. The more your marriage shows up across different areas of your life, the stronger the case. Texas offers the cleanest path because the Declaration of Informal Marriage creates an official record. In most other states you are assembling a paper trail from everyday life.

How You File

Once your common law marriage is established, your options are the same as any formally married couple: Married Filing Jointly or Married Filing Separately. You cannot file as single. Your marital status on the last day of the tax year controls the whole year.5Internal Revenue Service. Revenue Ruling 2013-17

Filing jointly produces a lower tax bill for most couples. Joint filers share a larger standard deduction and get wider tax brackets. For 2026, the standard deduction is $32,200 for joint filers compared to $16,100 for single filers.6Tax Foundation. 2026 Tax Brackets and Federal Income Tax Rates Joint filing also opens up or expands credits that phase out earlier for separate filers, including the Earned Income Tax Credit and education credits.

Filing separately fits narrower situations. If one spouse has large medical expenses, which are deductible only above 7.5% of adjusted gross income, separate filing lowers the threshold for that spouse. Separate filing also insulates one spouse from liability for the other’s tax debts or questionable deductions. The tradeoff is that many credits shrink or disappear, and the standard deduction is $16,100 per person with no way to combine.

The mechanics are simple. File Form 1040 and check the married box that applies. Both spouses sign. There is no separate form for common law marriages and no marriage certificate to attach. Keep your supporting documents in case the IRS asks later.

Penalties for the Wrong Filing Status

Trouble usually runs one direction: a couple that qualifies as common-law married files as single, either not realizing they meet the definition or hoping the IRS will not notice. If that error leads to underpayment, the IRS can impose a 20% accuracy-related penalty on the underpaid amount for negligence or disregard of the rules.7Office of the Law Revision Counsel. 26 USC 6662 – Imposition of Accuracy-Related Penalty on Underpayments If the misrepresentation is intentional, the penalty jumps to 75% of the underpayment attributable to fraud.8Office of the Law Revision Counsel. 26 USC 6663 – Imposition of Fraud Penalty Applied over several years of returns, even the 20% penalty adds up quickly.

The reverse creates the same exposure. Filing jointly to capture the larger deduction or better brackets when you do not actually meet the state’s requirements is equally incorrect, and the same penalty framework applies.

If You Move to a State That Doesn’t Recognize Common Law Marriage

A valid common law marriage does not expire when you cross state lines. The IRS has held since 1958 that a couple who entered a common law marriage in a recognizing state “shall, for purposes of Federal income tax filing status and personal exemptions, be considered married notwithstanding that the taxpayer and the taxpayer’s spouse are currently domiciled in a state that requires a ceremony.”5Internal Revenue Service. Revenue Ruling 2013-17 Publication 501 makes the same point by recognizing marriages valid under the law of “the state where the common law marriage began.”1Internal Revenue Service. Publication 501 – Dependents, Standard Deduction, and Filing Information

So a couple who established a common law marriage in Colorado and later moved to California, which does not recognize common law marriage, is still married for federal tax purposes and should keep filing as married. The wrinkle is that the new state may not recognize the marriage for state tax or other legal purposes, so your federal and state returns can reflect different statuses. Keep your evidence of the original marriage organized in case either taxing authority asks.