The Government has frozen all the assets of the man convicted of the March 15 mass murder and made it illegal to support his activities.
Prime Minister Jacinda Ardern announced this afternoon that she has designated Brenton Tarrant a "terrorist entity".
"Designating the offender is an important demonstration of New Zealand's condemnation of terrorism and violent extremism in all forms," Ardern said.
This designation means that it is now a criminal offence for anyone to be involved with Tarrant's activities.
"This designation ensures the offender cannot be involved in the financing of terrorism in the future," Ardern said.
It also means that all his assets – such as his bank account – have been frozen.
Ardern didn't name Tarrant in her statement, and would only refer to him as "a terrorist entity".
He has become the 20th person to be designated as such under New Zealand law.
"We have an obligation to New Zealand and to the wider international community to prevent the financing of terrorist acts," Ardern said.
The Prime Minister may designate individuals or groups as terrorist entities, on advice from officials, according to the Terrorism Suppression Act.
While living in his native Australia Tarrant had told people he received a $500,000 inheritance when his father died and an investment in crypto-currency had allowed him to live without having to work.
He had also travelled extensively around Europe, visiting sites where historic battles had taken place.
Special security measures for locking up the mosque gunman will cost taxpayers $3.6 million over two years, a Cabinet paper released last month revealed.
The cost averages just under $4932 per day - compared to the average cost of $302 per day for incarcerating a standard prisoner.