On December 3, some 3.3 million people are being returned about 2.2 billion euros in overpaid taxes.
The average tax refund this year is 665 euros.
However, nearly 800,000 people owe the state some 1.1 billion euros in unpaid taxes.
Taxpayers who owe the government face an average bill of 1,428 euros. If the back taxes amount to more than 170 euros, the Finnish Tax Administration divides the bill into two instalments.
The first back tax instalment was due on December 1 and the second falls on February 2, 2016.
