In 2007, Washington state-registered domestic partnerships were created to provide more equal benefits to domestic partners. In November 2012, Washington, Maine, and Maryland became the first states to pass same-sex marriage by popular vote - joining New York, Connecticut, Iowa, Massachusetts, Vermont, New Hampshire, and the District of Columbia in permitting same-sex marriage.
Washington's new law phases out domestic partnerships for everyone except for senior couples (one partner is 62-years-old or older). Same-sex domestic partners who are not seniors can either apply for a marriage license or wait until June 30, 2014. On June 30, 2014, the state will automatically convert registered domestic partnerships to civil marriages unless one of the partners is a senior.
If a registered domestic couple marries or their partnership is converted into a marriage, their legal date of marriage under Washington law will be the date the original domestic partnership was registered.
After June 30, 2014, domestic partnerships will only be available to senior couples.
A brief summary of the new law can be found here. For more information about how it may affect you, contact a Seattle family law attorney.