Kevin's lawyer Mark Vincent Kaplan said: "I was told of a general medical condition, and Britney Spears felt she couldn't attend.
"She's going to show at a later date, but we don't waive any rights to ask for certain relief from the court as a result of having a court-ordered deposition not attended."
Britney's friend-and-assistant Sam Lufti claims the singer was distressed by the media attention surrounding her court appearance.
He said: "She is sick, both physically and high anxiety. There are millions of people outside. It's too much."
A new date for Britney's deposition has been chosen, but not been revealed.
Her questioning, which isn't expected to last longer than a day, is set to address her alleged drug use, her failure to follow court orders and her capabilities as a mother.