The Parliamentary Audit Committee, which began the research about a year ago, is to hand its findings to parliament. Nearly 30,000 tax audits as well as close to 3,000 survey responses from various businesses were analysed.
According to the report, Finland's shadow economy has become far more international in the past decade. For instance, people dodge taxes by investing internationally. Finnish businesses have also been found taking advantage of lapses in EU monitoring.
The construction industry was responsible for the largest share of work done under the table. Hundreds of millions of euros go untaxed in the industry yearly.
Meanwhile, up to 90 percent of profits from international investments are not reported to tax officials. In practice, these investments are completely outside the realm of Finland's tax agency.
The findings and suggestions for reforms are to be sent to all government ministries and key labour market representatives for comment.