More than 21,000 people who have passed NCEA exams in the past 10 years have never been awarded the credits because their parents never paid the exam fees.
The lost credits have fallen into what Industry Training Federation chief executive Josh Williams calls "NCEA purgatory" - still accessible to training bodies, but not normally to employers.
"Most of our industries would say that NCEA Level 2 is increasingly a bit of a minimum. If people don't hold that, that would be a barrier," he said.
"To me that seems a bit cruel. If you think of NCEA as the culmination of all that compulsory education, and for the sake of $76, or $20, you don't give people the piece of paper that shows the labour market what they have got, that's a crazy policy."
Carterton construction worker Trent Grimmer, 25, passed his Level 2 at Wellington's Rongotai College but his mother, a beneficiary at the time, couldn't afford the $76 fee so he never received the credits.
"They would have been pretty helpful to me just to be able to show people that I had some qualifications," he said.
He only found out that he could still get the credits awarded by paying a late fee after he was sentenced in March to eight months on home detention for possessing a firearm and cannabis and receiving stolen goods.
His probation officer, who helped him get a variation to his sentence so that he could work at a frame and truss factory, also told him that he could still get the credits.
"I didn't actually know," he said. "No one had told me you could go back and bring up those credits, so I just made do with what I had at the time."
The NZ Qualifications Authority charges a flat fee of $76.70 a year to enter NCEA, the National Certificate of Educational Achievement. Students can enter any number of NCEA standards at no extra charge.
The fee can be reduced to $20 a student, or $30 a family, for families who qualify for community services cards. The income limits range from $49,993 for a sole parent with one child up to $85,852 for a two-parent family with four children, with higher limits for bigger families.
However parents must apply via the students' schools by September 1, and a $50 late fee is added to all fees paid after December 1.
Education Minister Nikki Kaye has told Green MP Catherine Delahunty in a written parliamentary answer that NZQA wrote to 22,127 students who had not paid their 2016 NCEA fees by the due date.
That was one seventh of the 154,835 students who entered NCEA last year.
NZQA deputy chief executive Kristine Kilkelly said 8395 of the late payers eventually paid up by the end of last week - leaving 13,732 who have still not paid last year's fees.
Many of them did not pass any credits anyway. But Kaye told Delahunty that 21,180 domestic students who entered NCEA over the 10 years from 2007 to 2016 "have one or more NCEA qualifications that have not been formally awarded due to unpaid fees".
Kilkelly said training providers could use a "Qual Check" procedure to see what students had achieved even if they did not pay the fees.
"NZQA can also provide the same information to an employer should we have the learners' express permission," she said.
But Delahunty called for the fees to be abolished, a call Williams endorsed.
"I don't think there should be such fees," Williams said. "If those students have achieved, they ought to be rewarded."
Students and their families paid $10.7 million in exam fees to NZQA last year, just over a quarter of the $38.5 million cost of administering secondary school assessments.
The Education Act guarantees "free education" to all New Zealanders between the ages of 5 and 19.
However the act also allows NZQA to charge "fees in relation to sitting for an examination".
Kilkelly said the NCEA fees had not changed since 2005, apart from a GST increase in 2010.
She said 26,970 students, or one in every six students who entered NCEA last year, were granted reduced fees because of low family incomes.
Work and Income also offers a loan of up to $200 for exam fees, which must be repaid over the next two years.