In order for a common law marriage to be found to be valid, the party must prove that the man and the woman, before two witnesses, declared their present intent to be married by saying to each other words similar to: “From this date forward, I consider you to be my [wife] [husband].” There are no “magic words”; they only need to convey a present tense intent to be married.

If you cannot prove such a ceremony, then you may be able to prove that you are common law married by proving that you held each other out to be Husband and Wife to community. You would do that showing that, for example, you both used the same last name, filed tax returns as married, introduced each other as Husband and Wife, paid bills in the married name, bought property in the married name, etc. There is no magic formula to prove that you are married; it is evaluated on a case by case basis.  Common law marriage is frought with problems. If you want to be considered married, this lawyer advises to get a marriage license and have a proper ceremony. Otherwise, you may think you are married, but what you think is not worth a hill of beans. It is up to a judge to decide. If you have a license and a ceremony, then there is no doubt. Otherwise, let the buyer beware!

DivorceNet - Common Law Marriage