David Alexander Nicholson is serving a sentence of two years and two months' jail after being convicted of almost $310,000 of tax evasion in July last year.
The 53-year-old appeared before the New Zealand Parole Board for the first time last month.
The board's decision revealed Nicholson was now engaged in outside work and received a good report about his behaviour in prison by the Department of Corrections.
He was also considered a low-risk of reoffending and was serving time in minimum security, but could not be paroled because he had no release plan in place, the board's decision said.
''Mr Nicholson ... told the board today that in fact coming into prison has turned him around both physically and mentally,'' the decision said.
''Given the serious offending which occurred over a lengthy period of time Mr Nicholson's risk remains undue at this time in the absence of a robust release proposal.
''Parole is declined.''
The decision also revealed Nicholson was made bankrupt in 2007 for not paying tax and child support.
The offending which resulted in his imprisonment took place from 2008 to 2010 and in 2013 and 2014, when Nicholson evaded $235,185 in income tax and $74,198 in GST.
''Mr Nicholson was solvent at all times and could have paid the GST and income tax on the due date,'' the board's decision said.
''In addition, at the time of sentencing, Mr Nicholson was continuing to trade as an IT consultant but was failing to comply with ongoing tax obligations. Instead, it appears he was paying back his historical tax obligations.''
Nicholson will again appear before the board in October.
