Washington doesn’t have common law marriage. What it has instead is a court-made rule called the committed intimate relationship, or CIR, which lets a judge divide the property an unmarried couple built together. This post is part of a series on how that rule works. It answers one question: what evidence you need to prove a committed intimate relationship existed.
Mostly paper, and mostly paper you already have. A judge deciding whether you were in a committed intimate relationship weighs five factors: continuous cohabitation, duration, purpose, pooling of money and effort, and mutual intent. Each one is proved with ordinary records: leases, deeds, loan applications, insurance enrollments, bank statements, tax returns, texts, and the forms where one of you named the other as partner or beneficiary. The dates matter as much as the documents, because the start and end of the relationship are almost always disputed.
Why the dates come first
A CIR case turns on a timeline. The start date decides how much property is on the table, because only property acquired during the relationship can be divided. The end date starts a three-year deadline to file, and it can come before anyone moves out: the Court of Appeals has held a CIR ends when one partner unequivocally tells the other it’s over. In re Parentage of G.W.-F., 170 Wn. App. 631, 648-49 (2012). Both dates are contested in nearly every case, and the partner with better records usually wins the argument.
In Washington the CIR can’t begin before you started living together. In re Marriage of Byerley, 183 Wn. App. 677, 689 (2014). In that case the difference between July and September 1996 decided whether a house was divisible. The couple signed the purchase agreement in July and moved in together in September, so the house was the buyer’s separate property. Two months of records changed the outcome.
Courts don’t always fix the start date at the move-in, though. In an unpublished 2025 Division I decision, In re Marriage of Coluccio and Khanlarova, the trial court set the start date at the day the couple signed wills and powers of attorney naming each other, years after they’d moved in together, and the Court of Appeals affirmed. Cohabitation “is . . . important, but it’s not the only factor.” So gather the evidence for every candidate date, not just one.
Evidence that proves a committed intimate relationship
When you moved in together
Leases with both names. Utility accounts. Renter’s or homeowner’s insurance listing both of you at the address. Driver’s license and voter registration address history. Mail forwarding. Texts and emails to landlords, movers, friends, and family about the move. If only one name is on the lease, look for the other partner’s mail, packages, and employer records showing the same address.
How long you were together, and any breaks
Photos with dates. Travel records. Holiday and birthday cards. Texts around any separation, including why it happened and how long it lasted. Be candid about breaks. An on-and-off relationship is a weaker case, and in an unpublished 2025 decision, Sammeth v. Ervin, Division I affirmed a finding of no CIR where the cohabitation wasn’t continuous, even though the couple had bought property together. The other side will find the breaks. Better that your lawyer knows first.
What the relationship was for
This is where you show the couple held themselves out as a family rather than as roommates. Employer benefit enrollments naming a domestic partner. Health insurance affidavits. Emergency contact forms. Beneficiary designations on life insurance or retirement accounts. Joint holiday cards. Invitations to any commitment ceremony. Records about children, including school forms listing both of you as parents or emergency contacts, and medical records showing who was at appointments or the birth.
Sworn statements carry the most weight. In Muridan v. Redl, 3 Wn. App. 2d 44 (2018), a domestic partnership affidavit signed to get health insurance counted as evidence of purpose and intent even though the motive was insurance. The partners had asserted under penalty of perjury that they were partners, and the court took them at their word.
Pooling of money and effort
Bank statements, even for separate accounts, showing the pattern: one partner paying the mortgage, the other paying everything else. Deeds and loan applications for anything you bought together. Title insurance and purchase and sale agreements, which in Byerley carried a partner’s name even though the deed didn’t. Records of a down payment and where it came from. Receipts for improvements to a home. Records of unpaid work in a partner’s business, including schedules, emails, and payroll records showing you weren’t paid or were underpaid. Joint debt. Tax returns, which can show who claimed whom and who reported what income.
Joint accounts help but aren’t required. In re Long and Fregeau, 158 Wn. App. 919 (2010). A couple that kept separate accounts and still ran a shared household can prove pooling through the spending pattern.
Intent
Wills and powers of attorney naming each other. Texts and emails about the future: buying a house, having kids, retiring together. Anything either of you wrote calling the other a partner, spouse, or family. And anything the other way. If your partner was married to someone else during part of the relationship, the divorce records and their living arrangements matter, because mutual intent is the factor that fails when one partner hasn’t committed. In re Marriage of Pennington, 142 Wn.2d 592, 604 (2000).
Evidence that hurts
Your own words are exhibits too. A text saying “we’re just roommates,” a loan application listing yourself as single, a tax return claiming head of household with no mention of a partner, or a lease you signed alone while telling family you’d moved in together. None of those is fatal on its own, but each one is something you’ll have to explain. Tell your lawyer about them before the other side produces them.
How the evidence gets into the case
A CIR case is a civil lawsuit, so both sides can demand documents and answers from each other through discovery, and can subpoena records from banks, employers, and insurers. In Island County, the family law rules require both parties in a CIR case to exchange financial records and allow 35 interrogatories. Island County LSPR 94(g). At trial, the judge hears the testimony, reviews the documents, and makes written findings on each factor. Whether a CIR existed is a mixed question of law and fact, so those findings are hard to overturn on appeal if the record supports them. Pennington, 142 Wn.2d at 602-03.
Two things you can do now
Save everything before you lose access. Download bank and retirement statements, screenshot texts, export emails, and photograph documents in the house. Once you move out or the accounts get locked, the records get harder to reach.
Build the timeline in writing. One page, dated: met, moved in, bought this, signed that, separated, reconciled, separated for good. Attach the document that proves each date. That page becomes the outline of the case.
Common questions
What evidence do you need to prove a committed intimate relationship in Washington? Records that show when you lived together, how long, that you presented yourselves as a couple, that you combined money and effort, and that you both intended a committed relationship. Leases, deeds, loan and insurance documents, bank statements, tax returns, texts, and forms naming each other as partner or beneficiary are the usual proof.
Do we need a joint bank account to prove a committed intimate relationship? No. Joint accounts help, but courts have found pooling from spending patterns across separate accounts, joint purchases, and unpaid work on shared projects.
Does a domestic partnership affidavit for health insurance count? Yes. In one Court of Appeals case, an affidavit signed to get insurance was treated as evidence of purpose and intent regardless of the motive, because the partners swore to it.
This post is part of our series on committed intimate relationships in Washington. Start with the main guide, What is a committed intimate relationship in Washington, and what happens when it ends?, or read about the Connell factors and the deadline to file after a CIR ends.
Last updated September 2026.
Law Offices of Daniel Ehrlich, Everett. Family law in Snohomish, Island, King, and Skagit Counties. (425) 954-5578.
This article is general information, not legal advice. Every case is different. If you’re separating from a partner you never married and there’s property between you, talk to an attorney.
