The unannounced visits to business and residential properties are part of an ongoing investigation into phoenix operators who set up businesses, load them with debts then fold them.

“We believe more than $40 million in tax revenue is at risk in this Sydney network alone and we have more than 100 officers involved in these visits,” deputy commissioner Michael Cranston said.

“The network includes tax agents and lawyers who may be helping to set up phoenix businesses. It also includes looking at whether liquidators may be working with fraudulent operators to help them evade paying their creditors. We are particularly concerned where third parties that are meant to be independent and transparent may be aiding dodgy business operators.

“Sometimes the element of surprise is needed to get a result, particularly when dealing with companies we suspect are setting out to cheat the system and where records may be destroyed if we give notice.”

Recent figures show that phoenix activity costs the Australian economy up to $3.2 billion each year, according to the ATO.