The British supermodel was reported to have married The Kills guitarist in a secret ceremony in Sicily, Italy, on August 7, but though they exchanged rings, the union is not legal.
Instead it is thought the Italian ceremony was a blessing, like that between Rolling Stones star Sir Mick Jagger and ex-model Jerry Hall in Bali in 1990, which Mick had annulled nine years later on the grounds it wasn't legally binding.
A source told the Daily Mirror newspaper: "When Jamie proposed, she accepted - but only after giving it a great deal of thought. She was adamant the wedding would be totally secret and very bohemian.
"Her friend Mick once joked to her that blessings were the way to go because they meant no loss of independence - financial or otherwise. Kate told Jamie their wedding would be as traditional and sacred as any other wedding, which is why they exchanged rings.
"There just wouldn't be as much paperwork."
The ceremony was also kept a strict secret, with even some of Kate's close friends, such as Sadie Frost, not invited to ensure nobody found out about the ceremony.
The source added: "Kate would go to any lengths to ensure it was covered up."
K ate and Jamie - who have been dating since September 2007 - were joined by just a few pals and relatives for the intimate affair in a small church.
A source said recently: "It was quiet - but still very romantic. Kate's had a fairly turbulent love life but she's a romantic at heart. The plans were kept very quiet as Kate wanted the day to be low-key and purely a Celebration of their love."
Jamie and Kate - who has an eight-year-old daughter, Lila Grace, with ex-boyfriend Jefferson Hack - were then reported to have danced around trees outside the church.