The Australian Tax Office says the money will start flowing at the beginning of May, backdated to the end of March - but first employers have to convince the ATO they're eligible.

To get the money, companies are wading through employment records to work out who is eligible. Staff on temporary visas will not get the payment, while some staff think the payment is a top-up to their normal wages.

No employer is biting the government hand holding out the lifeline but they do say they are dealing with a tidal wave of information emerging by the day.

Casino Canberra chief executive Allison Gallaugher said the scheme was a "good attempt to support businesses and employees in these unprecedented times".

There was no doubt the casino was eligible: "We are banned from opening and therefore our reduction in turnover is 100 per cent.

"A horrible situation to be in, but straightforward from an assessment point-of-view."

But she cited a string of issues.

"Employee expectations - we have had a lot of employees who are expecting that they will get $1500 in addition to whatever they are being paid," she said.

"Some employees are continuing as normal, others are on part-hours, others are taking leave, others are on full stand down with no pay.

"For those who are working as normal and earning over $1500, they won't receive anything different. However, many are expecting to get their salary plus a bonus $1500, not understanding that this is a subsidy to the employer, not a payment due straight to the employee."

Different employees will be treated differently.

"As a casino and restaurant operator, we have an extremely multicultural workforce, probably the most multicultural workforce in Canberra. However, as such, not all of our employees are yet citizens or permanent residents. That means that many of our team will actually miss out on this support, which for us is a huge concern," Ms Gallaugher said.

The government payment to the company would be much later than the company's payment to its workers.

"This is the hardest part of the policy, in that the employer must fund the payments and wait for the middle of the following month for reimbursement," the casino executive said.

Other, smaller companies are also wrestling with the scheme, according to Robert Shelton, managing director of accountants DFKEveralls.

Executives feared their enterprises could have to repay big sums of money if they got it wrong through no fault of their own.

He cited the example of a company which claimed for three workers who then turned out to be ineligible after three months: would the company have to pay back the $27,000?

"That's digging a very deep hole very quickly," Mr Shelton said.

Companies were asking how flexible the scheme would be, according to Graham Catt, chief executive of Canberra Business Chamber. If revenue had fallen just short of the required amount, would they still be eligible?

Unions report some companies have failed to apply because they had workers who weren't officially on the books.

The leader of UnionsACT, Alex White, said he knew of businesses which hadn't applied because they had been employing people on low wages by the back door.

They didn't want the ATO to look at the books. "The employer has no legitimate record of people being employees," he said.

The ATO has opened a route for employees to register their employer if the company seems reluctant - though the company would then have to cooperate by providing financial information. No financial information - no JobKeeper payment.

On Thursday, Prime Minister Scott Morrison warned employers if they didn't give the full amount to employees there would be trouble.

"That sort of behaviour where it occurs by employers is disgraceful and it's illegal," Mr Morrison said.

"And they should be reported to the police and the ATO. It's not on. It is really appalling behaviour. We will move quickly on that."