Calls are growing for big business to stop treating small business like banks by paying invoices late - if necessary by regulation.

Accounting software company Xero, which every month tracks payment times using data from its customers, said it was time to put pressure on large enterprises to stop using small business for working capital.

"Cashflow is the biggest killer of small business," said managing director New Zealand and Pacific, Craig Hudson.

"The flow-on effect [of late payment] is more far-reaching than we think. We need to be able to put pressure on big business to be supporting small business,