Pensioners will get a one-off payment to help with their electricity bills this winter.
Just days out from Tuesday's budget, Treasurer Scott Morrison says pensioners will get a $75 payment for singles and $125 for couples, which will be paid before June 30.
"That's specifically because of increasing electricity prices," Mr Morrison told the Nine Network on Sunday.
"It will be for aged pensioners, disability support pensioners, single parent payments."
The payments were the result of a deal struck with crossbench senator Nick Xenophon to help pass the government's business tax cuts earlier this year.
Mr Morrison's second budget will also include a $350 million boost to help defence force veterans battling mental health conditions.
Government frontbencher Darren Chester some of the younger veterans are struggling with life after defence.
"It is one area we can do more work," Mr Chester told ABC television.
"Making sure they get the help they need when they need it, that it has to be timely, effective and they have to be able to get it straight away."
News Corp Australia reported the government would spend $220 million on mental health, suicide prevention and programs to help personnel transition to civilian life, as well as addressing problems with the claims system for veterans seeking financial support.
There will be more than $30 million for non-liability mental health services to ex-servicemen and women who will no longer have to prove their mental health condition is linked to their service before receiving treatment.
It will also spend $10 million on suicide prevention programs, which will include a pilot program that provides case management for veterans after they are discharged from hospital.