DUP leader Arlene Foster is due to appear before the Renewable Heat Incentive (RHI) inquiry next month.
The former Stormont first minister is expected to give evidence from April 12 to 13.
Mrs Foster was the Stormont Enterprise Minister at the time the scheme was launched in November 2012. It is expected that the focus of the sessions will be evidence in relation to the early phases of the project and its operation.
Former DUP special adviser Andrew Crawford is also scheduled to appear before the inquiry on April 11 and 12.
He was named as the special adviser who had used his influence to delay the reduction of the scheme's excessively high tariffs. His name was given to the Public Accounts Committee by senior civil servant Dr Andrew McCormick.
Dr Crawford has denied the claim, saying he "acted with complete integrity".
However, he resigned the day after being named by Dr McCormick.
The RHI Inquiry was established to investigate the botched scheme, which was aimed at providing a financial incentive for businesses to move away from non-renewable sources of energy to renewable sources.
But applicants were able to make money by burning more fuel than needed as there was a lack of proper costs controls established on the scheme.
The judge-led inquiry was established last year by the then finance minister Máirtín Ó Muilleoir, with a million pages of documentation and public evidence hearings. A final report is not expected until later this year.
