Car owners are waiting an average of nearly 25 days to get an NCT appointment.
The Road Safety Authority says lead-in times have doubled since 2020, with Covid and staff shortages being blamed.
Mechanics from Spain and the Philippines are being flown here to try to clear the backlog, with some drivers waiting up to six months to have their car checked for its roadworthiness.
The Road Safety Authority will answer questions before the Oireachtas Transport Committee this afternoon.
Committee Chair, TD Kieran O'Donnell, says the delays are unacceptable.
