The building and construction industry will be the next main target of the taxman's attempts to claw-back revenue lost due to the illegal cash economy.

The Australian Taxation Office has visited over 1000 building and construction small businesses over the past financial year to talk with them about their tax and superannuation obligations.

It will be visiting thousands more in the coming months. And it's now using social media to catch out tax cheats.

Assistant Commissioner Matthew Bambrick told Fairfax Media the top three risky industries were hospitality, made up of 70,000 businesses; hair and beauty salons, of which there are 50,000; and building and construction, made up of 406,000 businesses.