Noting that the pair are trying to keep their wedding plans under wraps, a source told Us Magazine, "Kat and David are so elated and cannot wait to get married."
The insider added,
At the end of the day, this is a period of love and happiness for them and no one else. They complete each other.
The couple was spotted outside a Beverly Hills courthouse on Friday, May 16, and David appeared to hold the papers.
David 69, and Katharine, 35, became engaged after he proposed her during a romantic vacation in Italian in July 2018. Their engagement had come after dating for more than one year.
Page Six reported in February that the Canadian musician and the American Idol alum were planning a summer wedding in London.
Katharina was previously married to Invasion star Nick Cokas. The former couple tied the knot in 2008 getting a divorce in 2016.
For more updates, stay connected with Frostsnow.