In December 2009, Germany introduced an exemption from Real Estate Transfer Tax (RETT) for group restructurings.The exemption was challenged in the case of an upstream merger as infringing the State aid rules.
The CJEU found that although there was technically state aid, it could be justified "by the nature or general scheme of the German tax system and the intention of the German provision to prevent double taxation" (it being assumed that RETT had already been paid by the group).
See further here
