Finland's 'national envy day', when tax details of the country's top earners are made public, was mired in controversy on Monday as a new law allowed some individuals to hide their earnings from the media.

The Nordic country has a tradition of earnings transparency, with citizens' income for the previous year -- and crucially, how much tax they paid -- published in the media at the start of November.

Public tax data is seen by many Finns as an important marker of the country's commitment to equality and welfare. The tax administration claims that 95% of residents are happy to pay tax in return for high standards of public services, education and healthcare.

However, this year, Finland's Chancellor of Justice announced it would investigate complaints into a decision by Finland's tax office to allow 200 individuals earning more than 100,000 euros ($111,000) to keep their names off the media's rich list.

Jouni Kemppainen, editor of the newspaper Maaseudun Tulevaisuus, attacked the tax office's decision as "a question of principle for a democratic and open welfare society".

Finland may lack light in the autumn, but there's always national envy day to brighten the mood
Finland may lack light in the autumn, but there's always national envy day to brighten the mood LEHTIKUVA / VESA MOILANEN

Meanwhile professor of administrative law Olli Maenpaa told newspaper Kauppalehti that the tax office's claim that publication breached new EU data protection laws was not justified.

Noora Kontro, senior advisor at Finland's tax administrator, said that the office agreed to the 200 withholding requests for "economic, social or health and security-related reasons".

She added that although the names of the individuals have not been released to the newspapers, their incomes can still be looked up by any member of the public at a tax office.

Based on data made public, Finland's highest earners last year were two founders of the games company Supercell, Ilkka Paananen and Mikko Kodisoja, who pocketed 109 million euros and 98 million euros, respectively.

Among the top 100 names on this year's top earners list just 10 were women, of whom the highest-paid was Maria Severina, who last year earned 36 million euros from the sale of biotechnology firm Hytest.