The Turnbull government has clawed back $4 billion from the budget deficit by making billions of dollars in savings from payments to disabled people, students and the unemployed.

The figures from Tuesday's final budget outcome show the government saved $1.1 billion on payments for services for disabled Australians between July 2016 and July 2017.

"On the spending side the largest item in terms of less-than-expected expenditure is lower than anticipated payments to the National Disability Insurance Scheme reflecting a more gradual transition of participants," Treasurer Scott Morrison said in Sydney on Tuesday.

The government says the saving is also a result of fewer people being dependent on government support.