Victim Support chief executive Tony Paine said the levy was now "a really significant and positive part of the justice system".
"It's generating a significant amount of money, almost all of which is being channelled directly back into the pockets of victims of the very most serious crimes, particularly homicide and sexual violence."
It was appropriate offenders contributed to making things easier for victims, Mr Paine said.
"Even if their crime hasn't involved a victim, it just helps contribute to making the world a better place."
To date, $11.8 million nationwide has been raised by the levy, helping more than 4000 victims of serious crime.
Minister of Justice Judith Collins said it was critical that victims had the support they needed to be part of the justice process, and to help them recover and rebuild their lives.
The $50 levy is imposed on all offenders at sentencing and contributes to support services for crime victims.
A single levy is imposed, regardless of how many charges for which a person is sentenced.
Sensible Sentencing Trust spokesman Garth McVicar said the levy was a trust initiative.
"We wanted to move victims to having more of a voice in the justice system, but we didn't want to copy-cat the legal aid system. We felt it was wrong that the taxpayer should have to fund it so we wanted it to be funded by the people who were causing the harm - the offenders."
Mr McVicar said he hoped the current 14 per cent non-repayment rate was due to offenders being in prison, not "some giving their fingers to the system".
Offender levies cannot be collected from serving inmates but prisoners are required to pay up on release.
The order of payment priority is that reparation is paid first, followed by the levy, then any fines the person might owe.
In the 2011/12 financial year, $1.2 million was spent supporting 834 victims through the sexual violence court support service, Justice Ministry figures show.
In the same period, $115,000 was spent supporting 36 victims through the ACC additional funeral grant for families of homicide victims.
Also funded is a court attendance grant for up to five adult members of a homicide victim's family to attend proceedings and a discretionary grant for victims of sexual violence.
By the numbers
$270,880 paid in offender levies at Hastings District Court from July 1, 2010 to April 30, 2013
$230,519 paid in offender levies at Napier District Court
$40,551 paid in offender levies at Wairoa District Court
$11.8 million raised from offenders
$7.3 million spent on victims' services
- Source: Ministry of Justice