A top aide to Kansas Gov. Sam Brownback has hinted that the governor’s forthcoming plan to cut income taxes will also affect the state sales tax.

Brownback declined to discuss the details Thursday during an interview with The Associated Press. He says the plan is still in development, and he’ll release it Jan. 11 in his annual State of the State address.

Brownback policy director Landon Fulmer told the State Board of Education earlier this week the proposal will include a sales tax provision. But Fulmer provided no additional information.

Brownback has said his income tax cuts will be offset elsewhere, so that the state doesn’t lose revenue overall. The Republican governor said Thursday that he wants to make the income tax simpler and fairer.