The extended waiting time will apply to paid parental leave, the Carers Allowance and the Family Tax Benefit.
The government says the new measure will save $1.3 billion over the next four years.
But community groups are saying it'll come at a great cost.
Mary Patetsos is the chair of Federation of Ethnic Communities' Councils of Australia, or FECCA.
She has told SBS the move is unfair on new migrants.
The extended waiting time will apply to paid parental leave, the Carers Allowance and the Family Tax Benefit.
Ms Patetsos says migrants have always needed help to establish themselves in housing and employment.
She says women and families will be hit hardest by the extended waiting time.
But Finance Minister Matthias Cormann is admant it's the right move.
He has told Sky News the government doesn't wan't migrants on welfare payments as soon as they arrive.
Mr Cormann's comments come as human rights groups continue to protest the government's treatment of hundereds of refugees in Papua New Guinea.
Greens leader Richard Di Natale says the government should look at offshore detention centres for a money-saving alternative.
FECCA say they're worried about the long term effects the new laws will bring.
Ms Patetsos says the budget savings aren't worth the impact some migrants may feel.
