No.  In Iowa a common law marriage can be recognized after any length of time.  A common law marriage will give a couple rights as if they were married.  It will also give an individual the right to claim the property of their deceased “spouse”.  To determine if a common law marriage exists the court will look to see if there was an intent or agreement between the couple, if the couple was living together continuously, and that the couple were holding themselves out as man and wife and other factors.  Factors to prove these include such things as introducing the spouse as Mr. and Mrs. Jones, filing taxes as a married couple, writing your name on your mail as Mr. and Mrs. Etc.   See In Re Marriage of Winegard 278 N.W.2d 505 (1979).