Mr Ibrahim said the delay had caused hardship for its members and their families.
The federal government said the debts were revealed in data aggregated from over 5,000 debtors across more than 93 MDAs.
Mr Sumaila warned that FCT-IRS would not issue tax clearance certificates on WHT credits wrongly sent to other tax jurisdictions by the GIFMIS platform.
President Muhammadu Buhari named Mr Okolieaboh to the position in June 2022 following the dismissal of Ahmed Idris, the former accountant-general, over graft charges.
The agreement was reached on Friday.
