Witnesses at the Oireachtas Banking Inquiry have been asked to swear an oath on the Bible.
The chairman and CEO of NAMA have been asked to promise they will "tell the truth, the whole truth and nothing but the truth".
It is the first time that witnesses have been asked to take an oath ahead of a hearing.
Today marks the first of more than 60 hearings as the inquiry begins its 'Nexus phase' dealing with the events leading up to the bank guarantee.
NAMA executives will give evidence today, with the inquiry now focusing on the bank guarantee.
Between now and September, 64 public hearings involving at least 60 witnesses will be held.
The inquiry will hear from former politicians including Brian Cowen and Charlie McCreevy, bankers and the former governor of the central bank.