A class at Auckland's Western Springs College was given the wrong exam meant for the next year's class - and no one noticed.

The Year 12 class of 17 was supposed to be given a Level 2 Digital Technologies Common Assessment Task (DigiCAT) paper - but was given the Level 3 DigiCAT instead.

Principal Ivan Davis said the exam was supplied electronically by the NZ Qualifications Authority and the college's computer technician loaded it on to the students' laptops for the exam, which was taken a few days before the last date allowed, October 23.

"He inadvertently loaded a Level 3 exam on to Level 2 students," Davis confirmed.

"The students didn't notice. The teachers didn't notice. The IT technician didn't notice. We only noticed it after it had been all finished."

Davis said the students didn't complain that the exam was too hard and the mistake was only picked up when the completed exams were being collected to forward to the Qualifications Authority (NZQA).

The college alerted NZQA about the mistake on October 21 and had asked for advice on what to do.

"The students were worried that they would have to sit it again, and they were worried that their grades would be lower than they should be," Davis said.

He said some students might have passed the exam even though it was at a higher level than they expected, and the college suggested that they could have been given Level 3 credits for it.

However NZQA ruled that this was not possible because the students had not been taught the Level 3 material, so it decided to invoke an "unexpected event grade" process in which students have been given Level 2 credits derived from their previous work.

The DigiCAT, a compulsory part of Digital Technologies, is worth six credits towards Level 2 of the National Certificate of Educational Achievement (NCEA), which requires a total of at least 60 Level 2 credits plus at least 20 at Level 1 or above.

The mistake has come to light just before 140,000 students nationally begin the main NCEA exams on Monday, November 16. The exams are 10 days later than usual because of this year's Covid-19 lockdowns.

NZQA has been blamed for a series of mistakes in NCEA exams in recent years, but in this case the mistake was made by the college.

Davis said no one would be disciplined as a result.

"Our IT manager is meticulous in his work. He is beating himself up about this. He just feels absolutely terrible that it happened," Davis said.

"It's one of those trust things. Richard has done this [managed digital exams] so long, we trust that he has done it right. No one thought that it wouldn't be the Level 2 exam that was asked for.

"I would be confident in saying that it would never happen again, because it happened once."