IRS Common-Law Marriage Rules for Federal Taxes

The IRS common-law marriage rules are simple at the core: if the state where you and your partner began living as a couple recognizes your relationship as a valid marriage, the IRS treats you as legally married for every federal tax purpose. That recognition comes from Revenue Ruling 58-66, which the IRS reaffirmed in 2013, and it sticks with you even if you later move to a state that requires a ceremony.¹ Once your common-law marriage is established, filing as Single is no longer an option. You must file Married Filing Jointly or Married Filing Separately.

How the IRS Decides Whether You’re Married

The IRS has no independent definition of common-law marriage. It looks to state law, and specifically to the law of the state where the relationship was formed. Under Revenue Ruling 58-66, a couple who entered into a common-law marriage in a state that permits one is treated as married for federal income tax purposes, including the right to file joint returns under 26 U.S.C. § 6013.² No marriage certificate is required. What matters is whether your relationship met the legal requirements of the state where it began.

Move to a non-recognizing state after you’re already common-law married, and you stay married in the eyes of the IRS. The agency has held this position since 1958 and confirmed it applies to same-sex couples after Windsor and Obergefell.¹ The reverse is also true: if your state did not recognize common-law marriage when your relationship began, the IRS cannot treat you as married no matter how long you’ve lived together.

Getting the status wrong has a price. Filing as Single when you are legally married under state law is an incorrect filing status, and the IRS can assess a 20% accuracy-related penalty on any resulting underpayment, plus interest from the original due date.³ Filing as married when your state doesn’t actually recognize the relationship can trigger penalties and disallowance of credits like the Earned Income Tax Credit.⁴

Which States Recognize Common-Law Marriage

Only a handful of jurisdictions currently allow new common-law marriages. As of 2025, those are Colorado, Iowa, Kansas, Montana, Oklahoma, Rhode Island, Texas, and the District of Columbia.⁵ Utah recognizes unsolemnized marriages, but only after a couple petitions for a judicial or administrative order validating the union, which sets it apart from a traditional common-law state.

Several states abolished common-law marriage but still honor unions formed before a cutoff date. Alabama stopped allowing new common-law marriages on January 1, 2017; South Carolina’s cutoff was July 24, 2019. Pennsylvania, Georgia, Ohio, and Idaho made similar changes in earlier decades. If your common-law marriage began in one of these states before the cutoff, the IRS still treats you as married.

New Hampshire is a boundary case. State law deems a couple legally married only upon the death of one partner, and only if they cohabited, acknowledged each other as married, and had that reputation in the community for at least three years.⁶ That recognition applies for inheritance and survivor purposes. It doesn’t let living couples file joint tax returns.

What the States Typically Require

Specifics vary, but common-law states generally look for three elements: a present agreement between both partners to be married, cohabitation as a married couple, and publicly holding yourselves out as married.¹ “Present agreement” means you both intend to be married now, not at some future date. Cohabitation means living together on an ongoing basis. Holding out means the people around you, from neighbors to employers, understand you as a married couple.

Some states add capacity requirements. Utah requires both partners to be of legal age and capable of entering a solemnized marriage. Kansas and several others require legal capacity to marry, meaning neither partner can already be married to someone else.⁵ If the IRS questions your marital status during an audit, the burden is on you to show every element required by your state was met.

How To Prove a Common-Law Marriage to the IRS

There’s no federal registry of common-law marriages, so if your filing status is challenged, you rely on documentation. Two categories carry the most weight: evidence that you combined your financial lives, and evidence that you presented yourselves publicly as married.

Financial evidence looks like the ordinary paper trail of a married couple. Joint bank accounts. Shared credit cards. Mortgages or leases with both names. Co-owned real estate or vehicles. Insurance policies naming the other partner as a spouse or primary beneficiary. Anything that shows economic partnership on an ongoing basis.

Public representation evidence fills the other half. Signed affidavits from friends, family members, neighbors, clergy, or coworkers confirming they understood you to be married can be highly persuasive, especially when the statements describe how long the person observed the relationship and what led them to that understanding. Notary fees for these affidavits generally run from a few dollars to about $25 per signature.

Prior tax returns filed as Married Filing Jointly or Married Filing Separately are particularly strong because they show you consistently claimed married status over time. The Social Security Administration looks for similar documentation when evaluating common-law marriage claims, including signed statements from the surviving spouse and from relatives of both partners.⁷

One detail trips people up. The date your common-law marriage began must be consistent across all your documentation. If affidavits point to one year and your first joint return implies another, the IRS will notice. That start date determines when your obligation to file as married kicked in, and how many prior returns may need correcting.

Your Two Filing Options

Once your common-law marriage is valid under state law, you have the same choices as any married couple: Married Filing Jointly or Married Filing Separately. Head of Household is available only if you meet the special separation requirements. Single is off the table.

Married Filing Jointly

Joint filing is the better deal for most couples, particularly when one partner earns significantly more. For 2026, the joint standard deduction is $32,200, compared to $16,100 for a single or separately filed return.⁸ Joint filing also unlocks credits that are unavailable or severely limited on separate returns, including the Earned Income Tax Credit, the Child and Dependent Care Credit, and education credits.

The tradeoff is liability. Joint filers are jointly and severally liable for the entire tax bill, meaning the IRS can pursue either of you for the full amount owed. If your partner underreports income or claims bogus deductions and you had no idea, you can seek innocent spouse relief under 26 U.S.C. § 6015.⁹ That relief comes in three forms: traditional innocent spouse relief when you did not know about an understatement, separation of liability for couples no longer together, and equitable relief as a catch-all. The deadline to request most forms of relief is two years after the IRS begins collection activities.

Married Filing Separately

Filing separately is rarely cheaper, but it has its place. The MFS standard deduction is $16,100 for 2026, exactly half the joint amount.⁸ Beyond the smaller deduction, filing separately disqualifies you from most education credits and the adoption expense credit, and makes claiming the EITC nearly impossible unless you lived apart from your spouse for the last six months of the year.¹⁰

Roth IRA rules hit MFS filers especially hard. If you lived with your spouse at any point during the year, your ability to contribute phases out entirely once your modified adjusted gross income exceeds $10,000. That threshold isn’t adjusted for inflation.¹¹ For most working adults, that effectively shuts the door on Roth contributions while filing separately.

MFS makes sense in narrower circumstances: when one spouse has large itemized deductions reduced by adjusted gross income, like medical expenses above the 7.5% floor, or when one spouse wants to limit exposure to the other’s tax debts. Each separately filing spouse is responsible only for the tax on their own return.

Community Property Wrinkle for MFS Couples

If you’re in a common-law marriage, live in a community property state, and file separately, you can’t just report your own earnings. Each spouse must report half of all community income on their separate return, plus all of their own separate income. The nine community property states are Arizona, California, Idaho, Louisiana, Nevada, New Mexico, Texas, Washington, and Wisconsin.¹²

This creates a real complication for common-law couples in Texas, which is both a common-law marriage state and a community property state. Separately filing spouses must each attach Form 8958 showing how community income and deductions were divided. Business expenses tied to community income are split equally; expenses tied to separate income stay on the earning spouse’s return. Medical expenses paid from community funds are split equally as well.¹² IRA deductions are the exception, always figured separately for each spouse regardless of community property rules.

Fixing Prior Returns Filed as Single

If you and your common-law spouse filed as Single in years when you were legally married, you should consider amending those returns on Form 1040-X. The IRS requires an amended return when your filing status was wrong, and switching to a joint return often produces a refund.¹³

You can claim a refund only if you file the amended return within three years of the original filing date or within two years of paying the tax, whichever is later. Returns filed before the April deadline are treated as filed on the deadline for this purpose.¹⁴ If your common-law marriage began years ago and you’ve been filing incorrectly the whole time, you can typically only recover refunds for the most recent three tax years. Older years are past the refund deadline, though the IRS generally won’t penalize you for those years when the error resulted in overpayment.

One wrinkle: if either spouse filed separately and wants to switch to a joint return for a past year, the IRS allows the change. But once you file jointly, you generally cannot switch back to separate returns after the filing deadline has passed.²

You Can’t End It Just by Splitting Up

A common-law marriage doesn’t end when you move apart or decide you’re no longer together. The IRS considers you married until a court issues a formal divorce decree or annulment, and you must keep filing as married until then. Dissolving a common-law marriage follows the same process as any other divorce: petition a state court, get a decree, and the court sets the date your marriage ended.

Property transferred to your former spouse as part of the divorce settlement is generally a non-taxable event under 26 U.S.C. § 1041. No gain or loss is recognized on transfers between spouses or former spouses when the transfer is incident to the divorce.¹⁵ The receiving spouse takes over the original owner’s basis, so tax on any built-in gain shows up when they eventually sell, not at the time of transfer. Retirement accounts move tax-free only through a Qualified Domestic Relations Order, which lets a court direct that part of one spouse’s plan be transferred to the other and rolled into their own IRA without the early withdrawal penalty.¹⁶

For any divorce or separation agreement finalized after December 31, 2018, alimony payments are neither deductible by the payer nor included in the recipient’s income, and this applies equally to common-law marriage dissolutions.¹⁷ Once the divorce is final, your filing status changes. If you have a dependent child living with you and paid more than half the cost of maintaining your home, you may qualify for Head of Household, which offers a $24,150 standard deduction for 2026 and more favorable brackets than Single.⁸ Otherwise you file as Single.

1
Internal Revenue Service. Revenue Ruling 2013-17
2
Office of the Law Revision Counsel. 26 USC 6013 – Joint Returns of Income Tax by Husband and Wife
3
Internal Revenue Service. Accuracy-Related Penalty
4
Internal Revenue Service. Consequences of Filing EITC Returns Incorrectly
5
Department of Labor. Common-Law Marriage Handbook
6
New Hampshire General Court. New Hampshire Revised Statutes 457-39 – Cohabitation
7
Social Security Administration. Development of Common-Law (Non-Ceremonial) Marriages
8
Internal Revenue Service. IRS Releases Tax Inflation Adjustments for Tax Year 2026
9
Office of the Law Revision Counsel. 26 USC 6015 – Relief From Joint and Several Liability on Joint Return
10
Internal Revenue Service. Who Qualifies for the Earned Income Tax Credit (EITC)
11
Internal Revenue Service. 401(k) Limit Increases to $24,500 for 2026, IRA Limit Increases to $7,500
12
Internal Revenue Service. Publication 555, Community Property
13
Internal Revenue Service. Topic No. 308, Amended Returns
14
Internal Revenue Service. Time You Can Claim a Credit or Refund
15
Office of the Law Revision Counsel. 26 USC 1041 – Transfers of Property Between Spouses or Incident to Divorce
16
Internal Revenue Service. Retirement Topics – QDRO: Qualified Domestic Relations Order
17
Internal Revenue Service. Topic No. 452, Alimony and Separate Maintenance