The NCT has suspended the use of lifts at its 47 test centres around the country due to concerns over cracking.
Inspections have been taking place in recent days after "signs of cracking" were found in almost 50 lifts in the north.
The same company supplies lifts in the republic, and an initial inspection by the NCT found cracks in one lift.
It has now ordered the suspension of their use until a full audit can take place to establish the extent of the problem.
Drivers due for an NCT will still be able to take two-thirds of the test, but will have to return and take the final part once the issue has been resolved.
Reporting form Adrian Harmon