A teacher deregistered for a relationship with a former student now faces a $23,416 bill for costs from the Teachers' Disciplinary Tribunal.
The woman contested the sum saying she could not afford it, but the tribunal said the figure was reasonable.
The tribunal struck the woman from the teacher register earlier this year because she had formed a relationship with a former student from a youth justice facility when he was a teenager in prison.
It said the teenager was vulnerable because of his age and location.
The tribunal's report said the pair met in 2010 when the woman, then aged 32, became the man's homeroom teacher in a school at a youth justice facility. He was 16 at the time.
The teenager was transferred to a prison in September 2011 and the pair began a relationship in early 2013. He was released in September 2013 and they married in January 2016.
During hearings with the Education Council's Complaints Assessment Committee in 2015, the woman denied any sexual relationship and in December that year told the committee she had not really seen the man during the previous four years.
"However, she was living with him at the time and married him the following month," the tribunal's judgement said.
The tribunal's decision on costs said the woman had said she could not afford to pay half the $46,832 in costs.
But the tribunal said a two-day hearing and witnesses were required because the woman did not cooperate in the initial inquiry and denied allegations which were later proved.
The Education Council told RNZ the costs were higher than for most disciplinary tribunal hearings, but the case was not typical.