Small and medium-sized businesses are getting ripped off $7 billion a year because bigger businesses are not paying them $115 billion on time, according to a comprehensive study of invoicing from more than 150,000 businesses.

The research from ASX-listed business platform Xero and economists AlphaBeta is based on more than 10 million invoices and hopes to raise attention to the need for small business to invest in online invoicing technology and for government intervention.