Sixty-eight percent of sexual abuse and assault claims are failing to get through the ACC system.
Almost half give up their claims for long-term support, with advocates saying it's because the process is too traumatic.
Advocates say the low acceptance shows the system is not working for survivors, but the ACC Minister says it doesn't mean survivors are not getting the help they need.
Figures were obtained by RNZ under the Official Information Act, and also by Green Party ACC spokesperson Jan Logie.
Sex abuse survivors are pulling out of ACC's formal claims process because it's too stressful, Logie said.
"That really is a red flag for us to re-look at the process because it's not survivor centred."
Of the 10,335 sensitive claims lodged in the year ending 30 June 2020, 3291 claims were accepted. Just under half of all declined claims were withdrawn by the client.
But the low acceptance rate did not mean survivors were not getting help, ACC Minister Carmel Sepuloni said.
"Anyone making a sensitive claim gets up to 14 hours of therapy, 10 hours of cultural support, 10 hours of social work support and 20 hours of whānau support before deciding to undergo a formal assessment."
This assessment establishes whether the survivor has a mental injury as a result of the abuse, which makes them eligible for longer-term ACC cover.
Those who decline to undergo an assessment are recorded in ACC's system as being declined, says Sepuloni.
"It's the system's way of recording it as opposed to a true reflection of women actually having genuine claims turned down."
Of those survivors who do choose to undergo a formal assessment, 91 percent have their claim approved.
Advocates say they've been telling ACC for years that its assessments are flawed.
One support group says the requirement to have a mental health diagnosis in order to get claims approved puts many survivors off.
"An assessment requires bringing in a psychologist or a psychiatrist to essentially diagnose a client with the right type of mental illness to allow them to access long-term care from ACC," said the support group, which cannot be named because its ACC contract prevents it speaking publicly.
"They're medicalising it, whereas we know that is off-putting to a lot of survivors who don't want to come away with a mental health diagnosis, as it might show up for them in the future in their medical records or when they're applying for insurance.
"This highlights that assessment process isn't working and it's creating barriers for people getting help."
A formal assessment can also be re-traumatising for survivors as they often have to tell their stories over and over again to different agencies before even being referred to ACC, Women's Refuge principal policy advisor Natalie Thorburn said.
"Going through a supported assessment is often a prohibitively hard prospect for a woman to face when they're seeking counselling.
"Many health practitioners aren't aware that people can even get that funded support through an ACC claim, so they get passed around from person to person before getting a referral to an ACC-registered practitioner.
"Having to repeat their story and catalogue the range of impacts it's had on their lives can be retraumatising and deeply distressing.
"Having to do a lengthy supported assessment with yet another professional deters many women from continuing with their claim, and effectively lets ACC off the hook in terms of providing them with funded counselling."
ACC needs to stop treating sensitive claims the same as physical injuries, Thorburn said.
"The onus to go through an assessment is offensive. The process forces women to talk about what happened to them so that ACC can decide whether it's truthful and whether they need support.
"Victims know if they need support, and only they should be making those decisions.
"It is rare for people to lie about abuse, and the obligations placed on victims make it almost impossible for them to get the support they need."
ACC was unable to say how many sex abuse survivors had declined a formal assessment, or the reasons why. Sepuloni said she had asked the agency to look into the issue.
*This story originally said that 95 percent of sexual abuse claims did not make it through the ACC system. This data was provided to RNZ by ACC. That data was accurate but did not reflect all claimants who made sensitive claims, as some sexual abuse/assault claims were coded with terms other than 'sexual abuse'. The figures have now been changed to reflect all sensitive claims.
Where to get help:
Victim Support 0800 842 846
Rape Crisis 0800 88 33 00
HELP Call 24/7 (Auckland): 09 623 1700, (Wellington): be 04 801 6655 - 0
Safe to talk: a 24/7 confidential helpline for survivors, support people and those with harmful sexual behaviour: 0800044334.
Mosaic - Tiaki Tangata Peer support for males who have experienced trauma and sexual abuse: 0800 94 22 94
Women's Refuge: (0800 733 843)
It's Not OK (0800 456 450)
Shine: 0508 744 633
Victim Support: 0800 650 654
HELP Call 24/7 (Auckland): 09 623 1700, (Wellington): be 04 801 6655 - 0
The National Network of Family Violence Services NZ has information on specialist family violence agencies.
Lifeline: 0800 543 354 or text HELP to 4357
Suicide Crisis Helpline: 0508 828 865 / 0508 TAUTOKO (24/7). This is a service for people who may be thinking about suicide, or those who are concerned about family or friends.
Depression Helpline: 0800 111 757 (24/7) or text 4202
Samaritans: 0800 726 666 (24/7)
If it is an emergency and you feel like you or someone else is at risk, call 111.