An estimated 400 restaurants, cafes and hair and beauty salons will get a visit from the Tax Office this month, as part of the agency's continued focus on the illegal cash economy.

The ATO has in recent years stepped up audits of small businesses in high-risk industries, which it suspects may be taking illegal cash-in-hand payments.

ATO officers with Asian language skills have been visiting these kinds of businesses in major cities across Australia including Melbourne, Sydney, Gold Coast and Adelaide.

Assistant Commissioner Tom Wheeler said Perth and Canberra were next.