Tax authorities are auditing some of the country’s largest property, construction and hospitality companies over concerns that fictitious arrangements are being used to improperly claim GST refunds.

In a warning issued on Thursday, the Australian Taxation Office explicitly noted large companies in property, construction and hospitality were being monitored. The ATO’s investigation tools have flagged that an increasing number of these companies are likely to be wrongfully claiming, in some cases, tens of millions of dollars in GST refunds.