The transition was announced to a small group of Toyota executives on Friday, and the rest of the staff will be told on Monday, the sources said.
Toyota chief spokeswoman Julie Hamp declined to comment on the matter, calling it “rumor and speculation.”
Calls and e-mails to Plano city officials were not returned.
The relocation would mark the second time a Japanese automaker has left a headquarters in California where U.S. sales operations were established in the 1950s. Nissan North America transferred to Nashville, Tenn., in 2006.
The automaker had been expected to announce details of a change in its marketing operations this week.
An overhaul was expected to go into effect on May 1, Automotive News reported in February. That report said 80 employees would be required to reapply for newly created positions or take a voluntary separation.
In February, Toyota said employee roles and responsibilities were being redefined to be more "integrated, flexible and efficient."
The automaker said those changes were necessary "in order to meet our future business needs, and support our dealers and guests more effectively."
At the time, Jack Hollis, vice president of marketing for the Toyota division, said the company's marketing ranks will likely grow in the near future.
But because the operating structure of the department would be changing, some current employees might not have skill sets that match the new organization, Toyota said.