The whole idea of common law marriage is that it is just that - part of the common law (in countries that use a system of common law, like the U.K. and Canada, and not civil law, like France and the U.S.) and not part of any legislated rule that supersedes the common law. It gets decided on a case by case basis in the courts. Before there was any legislation governing these relationships, it was just a term applied to a couple living together in a marriage-like relationship, such that, if one partner was to sue the other for a share of property, a court would say they were entitled to a share. There was a famous case of a Canadian farm wife who, under legislation would have been entitled to nothing that was not in her own name or owned jointly with her husband, was found under the "common law" precedents that our legal system relies on to be entitled to a share in the value of the farm, based on her contributions as a partner in the relationship. Since in theory each relationship would be judged on its own merits it is not possible to say how many years are necessary to be considered "common law." However, many people have used legislated status to say they qualify as "common law" - e.g. tax laws that say you must file as a couple if you have lived together for more than a year (just an example, not sure if that is still true or not since I've been married quite a while now LOL). Long story short, if it applies to an historical relationship of a significant period of time you could refer to this as a common law relationship, or even a "marriage-like" relationship.