Spending on mental health services for children and adolescents varies seven-fold across England and Wales, according to an Audit Commission report that finds 'little relation' between spending and need.
It calls on health authorities and trusts to set up separate budgets for child and adolescent mental health services in order to take stock of their spending.
Audit Commission controller Andrew Foster said agencies needed to work together to 'provide better, more timely support for young people and their families'.
The report says 10 per cent of trusts could not offer an appointment for non-urgent cases within six months.
Only half of HAs had agreements for emergency and 24-hour cover and over a third of trusts felt that they 'could not respond effectively to young people presenting in a crisis'.
The audit of 60 per cent of HAs and 90 per cent of trusts commissioning or providing CAMHS highlights 'poor links' between specialist CAMHS and other agencies.
And it says groups responsible for commissioning CAMHS need to agree the scope of their services.
The Audit Commission found 29 per cent of commissioners limited services to those aged under 16, 'although adult services are not considered suitable by many for young people aged 16 and 17'.
Less than a quarter of the services surveyed had specific arrangements for transferring young people to adult services.
Mental health charity Young Minds said the report 'confirms much of what we knew already'.
'Enormous variations not only in terms of spending but also in the way services are run' showed there was a need for a national model for services, said director Peter Wilson. He said it was a 'scandal' that efforts ploughed into developing an adult national service framework for mental health would not benefit children.
The Mental Health Foundation also endorsed the report, saying a 'period of sustained and continuing investment' was needed to bring services up to scratch.
Mr Wilson urged the government to 'hurry up and spend' the£84m for services announced in February.
This week the first allocation of£16m, made up of modernisation funds and the CAMHS mental health grant, was made by health minister John Denham to schemes which had shown evidence of 'joint working'.