Update: The Illinois Department of Revenue has changed its mind. Couples in same-sex civil unions can file joint Illinois tax returns. Click here for more information.
Illinois now allows same-sex civil unions and recognizes same-sex marriages conducted outside the state — but it does not recognize those unions for tax purposes. The Illinois Department of Revenue says people in same-sex civil unions or marriages will not be able to file joint Illinois tax returns.
The Department bases its opinion on the fact that, by statute, Illinois filing status is based on federal filing status. And because of the Federal Defense of Marriage Act, married gay couples cannot file joint returns. Therefore, according to the Department of Revenue, they can’t file joint Illinois returns, either.