Australia Street: What do want to see in the budget?
Mr Frydenberg denied the move is a "cash splash" and said the payments are examples of "responsible, targeted spending".
"This is money that is going to go into people's pockets to help meet the cost of their next power bill," Mr Frydenberg told Nine's Weekend Today Show on Sunday.
3.9 million Australians to benefit
The payment will go to 2.4 million people on the age pension, 744,000 people on a disability support pension, and 280,000 people getting carer payments.
A further 242,000 people getting single parent payments will also get the extra cash, along with 225,000 veterans and their eligible dependents.
Finance Minister Mathias Cormann said the coalition's conservative approach to economic forecasts was paying dividends.
"From 2019/20 onwards our forecast and projections are for a surplus to be maintained all the way through the medium term over the next decade," Senator Cormann told Sky News.
Labor promises to re-write budget, if elected
But the April 2 budget may not last long. Shadow treasurer Chris Bowen has promised another one somewhere between July and September if Labor - as widely expected - wins the May election.
"If we win, we will bring down a major economic statement in the third quarter of the year, which will in effect be the first budget of a Shorten Labor government," he told ABC's Insiders.
"We need to reset the economic settings. We need to update the forecasts with the new government in place."
Mr Frydenberg pushed back against criticism that the government's surplus was built on huge underspending in the National Disability Insurance Scheme.
"It is a demand-driven program and as of the end of last year there were 250,000 people who were in the NDIS, 78,000 of whom hadn't received disability support before, and it is going to 460,000," he said.
"Everybody who is in the NDIS is fully funded through this government and through this budget."
Mr Frydenberg also argued that wages, which have stagnated in recent years, are picking up compared to this point last year.
But Mr Bowen said the coalition had over-estimated wage growth in every single budget it had handed down.
Prime Minister Scott Morrison is expected to call an election for May 11 or 18 within days of Tuesday's budget being handed down.