The Court of Justice handed down its judgment in the Meilicke case which concerned with the availability of tax credits for foreign tax on 30 June 2011. The Court followed the conclusions of Advocate General Trstenjak.

The Court held that a tax credit needed to be given for the amount of tax actually paid up to the limit of the domestic corporation tax rate. Equality of treatment should extend to the level at which tax is credited. Thus if domestically the system did not allow tax paid at a level lower than that of the company making the distribution to be taken into account for the calculation of the tax credit then the same should apply cross border, and vice versa.

To require a certificate for foreign corporation tax to be in the form prescribed by domestic law breached the principle of effectiveness if it was in fact impossible or excessively difficult to obtain such a certificate. However, national tax authorities are entitled to require the shareholder to provide evidence which allows them to ascertain whether a credit has to be given and, if so, in what amount. The fact that the member state could request that information under the mutual assistance directive did not mean that it had to exercise that right.

Finally the court confirmed its longstanding case law that retrospective legislation needs to provide a sufficient transitional period for it not to breach the EU law principle of effectiveness.