Association president Beven Hanlon has frequently attacked government policies.
His most recent targets have been privately-run prisons and the association is taking the Government to the Employment Court over double-bunking.
NZPA understands the Corrections Department paid the association and Mr Hanlon $127,727 in the 2008/09 financial year.
That included $44,889 to subsidise Mr Hanlon's salary for the two days a week he spends on union business and the amount to hire a replacement for those days.
Another $32,215 was paid in airfares, there was $3163 for car rentals and taxis, $6226 for accommodation and $41,233 for what is described in documents as "salaries and backfill".
Corrections Minister Judith Collins said she was "very concerned" by the amount being paid to subsidise the union.
"I also understand that this money from the taxpayer has allowed the union to amass close to $2 million in savings," she said.
"I would be interested to hear from the union how they can justify this and why they need funding from the taxpayer when it received union fees from members and has so much money supposedly in the bank."
The department's organisational development general manager, Vincent Arbuckle, said there would be a review of the long-standing support provided to the association.
"This work is now under way and I am unable to comment further at this point," he said.
Mr Hanlon could not be contacted last night.
