But casuals who have been with an employer for less than a year and foreign visa holders remain left out of $130 billion wage subsidy program, and the government has tightened rules to exclude full-time students younger than 17 years who are not financially independent.

In a blow to the higher education sector, the government has also "clarified" that core Commonwealth funding is included in the turnover eligibility test, making it tough for many institutions to qualify for the assistance.

The government has faced mounting criticism over anomalies and gaps in the JobKeeper program, which was set up to subsidise the wages of workers who otherwise faced losing their job or taking a substantial cut in wages.

Under the terms of the scheme, small and medium employers who suffered a 30 per cent or greater fall in turnover and larger firms who experienced a 50 per cent fall, would be eligible to join the scheme.

Eligible employers will from next month receive $1500 a fortnight from the Australian Taxation Office for each nominated employee, which they must pass on to their workers in full.

Around 900,000 businesses have expressed interest in the scheme, and Mr Frydenberg said more than 400,000 firms employing about 2.4 million workers have enrolled since the start of the week.

After many employers complained they were unable to get finance to cover their costs in the first stage of the scheme until funding begins to flow from the ATO, the government heavied the banks, who have agreed to set up business hotlines and bring JobKeeper financing applications "to the front of the queue".

The JobKeeper program is the centrepiece of the government's response to the economic damage caused by the restrictions imposed to slow the spread of the COVID-19 virus.

The scheme was passed by Parliament with bipartisan support after Labor failed in an attempt to expand it to include 1.1 million casual workers not currently covered by the program as well as temporary visa holders.

The government has been steadfast in refusing to expand JobKeeper to include casuals who have worked for an employer for less than a year, and for overseas workers.

In rejecting Labor's amendments, Mr Frydenberg said a "line had to be drawn" by the government at some stage.

The government has said that casuals ineligible for JobKeeper can instead apply for assistance through JobSeeker.

The JobKeeper scheme is due to wind up in September, and the government is facing calls to either extend it or replace it with some other substantial form of assistance.

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These urgings have been amplified by mounting evidence of the scale of the damage being caused by the social restrictions.

Reserve Bank of Australia govenor Philip Lowe has warned that output is set to shrink by 10 per cent in the first half of the year and total hours worked will collapse 20 per cent . Treasury has forecast unemployment to reach 10 per cent by mid-year.