The Albanese government is being urged to further cut its 8 per cent growth target for the ballooning cost of the National Disability Insurance Scheme and to fund new supports for children with autism from its existing $51 billion budget.

Reining in the NDIS is one of the major budget challenges facing Prime Minister Anthony Albanese and Treasurer Jim Chalmers as they grapple with official forecasts for a decade of deficits.