Solicitors for Rehab have contacted the Public Accounts Committee to say that the group's CEO, Angela Kerins, is not willing to discuss her salary when she appears before the Committee later today.
Representatives from Rehab are due to answer questions about the group's lottery scheme, and why it made so little money.
The Chairman of the PAC said Rehab's legal team have contacted them to say Ms Kerins is willing to discuss the €82m of state funding - but not her €240,000 salary.
"Yesterday we received a message from their legal advisor [on this]," said PAC chairman John McGuinness.
"I don't think there's any need for them to go to a solicitor to inform us that we need to be kept within our remit.
"I think it was a step too far. The members will deal with that in the course of today's hearing."
Mc Guinness said the committee would want to know what the salaries of senior managers were benchmarked against, as they amount to a "significant expenditure."
Committee member Mary Lou McDonald said she regards the statement from Rehab's solicitors as an almost "provocative gesture".