Last November, commission president Jean-Claude Juncker's mandate got off to a rocky start when it was revealed Luxembourg had given preferential tax treatment to a number of multinationals during the time he was prime minister.
As a result, parliament set up a tax rulings and other measures similar in nature or effect (TAXE) special committee to look into tax legislation that could be considered unfair for EU competition. The committee will issue recommendations to parliament's economic and monetary affairs committee, which is drafting two reports on the issue.
TAXE chair Alain Lamassoure said that the tax practices being looked into "may be in line with national legislation in the different member states, but it is scandalous and immoral from an economic, social and political point of view".
Yet he stressed that "we are not here to punish the bad guys as it were - that is for the justice system".
However, there are fears that the committee is running out of time, as its initial six-month mandate is due to run out in August.
The EPP deputy highlighted that, "we don't have too much extra time - we need to have the press and public opinion on board; there is still interest in 'LuxLeaks' but in a few months, people will have forgotten all of that, so if we want to be useful in what we're doing we should not be losing momentum".
Co-rapporteur Michael Theurer was of the same view, saying, "I am firmly convinced that we are not working quickly enough".
He added, "we must make up for lost time, if we don't then the committee will not reach its objectives".
The ALDE MEP warned that, "the reputation of the European parliament and its ability to respond to 'LuxLeaks' is at stake".
And GUE/NGL TAXE shadow rapporteur Fabio de Masi called the committee "toothless", underlining that, "even after two months, we have yet to see a single document from the member states".
Meanwhile, co-rapporteur Elisa Ferreira complained that "it is very difficult to explain to our citizens that this very Europe that is so strict when it comes to austerity can accept that taxes that should have been paid in some countries were completely circumvented and sent elsewhere through legal administrative mechanisms".
The TAXE committee has requested meetings with the finance ministers of all 28 member states, but Lamassoure said that so far only the Estonian and French ministers had accepted parliament's invitation.
In addition, the special committee has met with journalists and whistleblowers who were responsible for uncovering the 'LuxLeaks' revelations. Some of them, such as Antoine Deltour and Edouard Perrin, are now being criminally prosecuted.
MEPs have urged the commission to intervene, with S&D group TAXE spokesperson Peter Simon saying, "the fact that these people are subject to public repression due to their expression of civil courage is simply unacceptable. The European commission must eventually present an EU-wide legal framework which protects [them] from prosecution".
TAXE vice-chair Marisa Matias pointed out that, "according to a circular by the Luxembourg tax authorities dating from 1989, tax rulings that are mainly aimed at 'tax optimisation' are illegal. However, only whistleblower Deltour and journalist Perrin are being taken to court. This is a blatant attack on press freedom, right in the very heart of Europe."