The Ministry of Health says there have not been changes to rules for getting funding in autism cases.
Autism New Zealand says almost 150 people with the condition have been turned down for funding in the past eight months, leading to cuts in respite care, residential services and behaviour support services.
It says they are being declined funding because they have no intellectual disability or other condition.
Jill Lane, the ministry's director of national services purchasing, says it has seen a 43% increase in cases of people getting funding solely for autism since 2008.
"We're very keen to hear from people who feel that they may have had services that have changed. It's very clear to us that nobody should have services change unless their needs have changed."
Ms Lane says the ministry wants a consistent but flexible approach to assessing people's needs.
Autism New Zealand says there are cases of children being locked away or tied to furniture as desperate parents struggle to cope with the funding cuts.
It says families have tried appealing against decisions, but retraining of needs assessors in 2012 meant they have hit a brick wall.
Chief executive Alison Molloy said no funding means no respite care, residential services and behaviour support services, and more than 100 people have serious anxiety due to the cuts.