The Morrison government has announced a series of measures to help casual workers, sole traders, retirees and those on income support as part of its second $66 billion stimulus package in the face of the coronavirus.

Treasurer Josh Frydenberg said since announcing the first $17.6 billion package 10 days ago the global and domestic economic environment has deteriorated.

"We now expect the economic shock to be deeper, wider and longer," Mr Frydenberg told reporters in Canberra on Sunday.

The new measures include a new, time-limited coronavirus supplement to paid at a rate of $550 per fortnight to both existing and new recipients of the JobSeeker Payment, Youth Allowance jobseeker, Parenting Payment, Farm Household Allowance and Special Benefit.

This supplement will be paid for the next six months at a cost of $14.1 billion.

In addition to the $750 stimulus payment announced on 12 March, the government will provide a further $750 payment to social security and veteran income support recipients and eligible concession card holders.

The government is also allowing individuals in financial stress as a result of COVID-19 to access up to $10,000 of their superannuation in the 2019/20 financial year and a further $10,000 in 2020/21.

"These withdrawals will be tax-free and available to those who are eligible for the coronavirus supplement as well as sole traders who have seen their hours work, or income fall, 20 per cent or more as a result of the coronavirus," Mr Frydenberg said.