The NCT Service says it'll continue increasing capacity until the current backlog is cleared.
The service's operator, Applus, says an additional 50 inspectors are due to start training next month, following a recruitment drive in the Philippines.
That's in addition to 24 new inspectors who've already been recruited so far this year.
However, the wait time is still as long as nine months in some test centres.
Martin Kenny - Sinn Féin's Transport Spokesperson - says the delays cannot be tolerated for much longer.
"There needs to be something done obviously, because as we know the company that does the testing have recruited more people, they've brought people in from abroad, but there isn't the capacity there to deal with the situation.
"I think we really need to step up to the mark and come up with solutions for people, because we can't have a situation where people can't get their NCT done."
