Minister for Superannuation Nick Sherry has hit out at the Opposition's proposal to help small businesses with their cash flow by paying a part of their superannuation guarantee (SG) obligations.

Yesterday, the Opposition announced a proposal to pay a proportion of the SG for businesses employing less than 20 people for the next two years. "Under Mr Turnbull's plan, because of the sheer administrative complexity, it is almost impossible that any Government payment of superannuation could occur before the September quarter," Sherry said.

"Our economy needs a stimulus right now and we're acting decisively to deliver that."

Sherry has also questioned the costs that such a proposal would involve.

"Malcolm Turnbull hasn't even tried to cost the idea. I can advise that the impact of his latest plan, if it was only for the next two years, would be a staggering $20.5 billion," Sherry said.

"If it ran across four years this dangerous policy would, as a single measure, cost $43 billion - larger than our entire package."

However, the Opposition has disputed this costing estimation.

"The Government has falsely claimed that the cost would amount to $20.5 billion, yet have not revealed the underlying assumptions," Shadow Minister for Financial Services, Superannuation and Corporate Law Chris Pearce said.

"We're in the process of working out how much it would cost." 

Industry groups have had a mixed response to the Opposition's proposal.

"At this stage we haven't seen any evidence that businesses are not able to meet their Super Guarantee obligations," Australian Institute of Superannuation Trustees chief executive Fiona Reynolds said.

"However, if evidence did come to light that this was the case then we would welcome moves to ensure that employers received their super entitlements."

The Association of Superannuation Funds of Australia chief executive Pauline Vamos said the long-term impact of such stimulus proposals was unknown.