Common Law Marriage in Illinois

Living together for a long time does not by itself create a marriage. Where common law marriage is allowed, the key question is usually whether both partners agreed to be married and acted that way in public, for example by using the same last name, filing joint tax returns or calling each other husband or wife.

A valid common law marriage can only be ended by divorce or death, just like a licensed marriage. There is no informal way to undo it by moving out. The question of whether a marriage existed often comes up later, in a divorce, an inheritance dispute or a claim for spousal benefits.

Couples who want clear proof of their status can sign a written declaration or affidavit of marriage where state law provides for one, or simply obtain a marriage license. Couples who live together and do not want to be married can sign a cohabitation agreement that sets out how property and expenses are handled.