Britney Deposed!!!

TMZ has learned Britney Spears will finally take the oath and have her deposition taken -- and it's happening tomorrow at 10 AM.

Sources say Britney will roll to the Los Angeles offices of K-Fed's lawyer, Mark Vincent Kaplan. Her legal team, which includes Anne Kiley and Tara Scott, will be there to raise objections -- and expect lots of them.

Those sources say the depo could last several days. Kaplan has been trying to get Brit under oath for nearly a year and he'll be asking a range of questions relating to child custody and, we believe, spousal support.