When moving into a new house, some people organize a Qur'aan khatam.

Answer

It is bid'ah. There is considerable barkat and benefit in reciting the Qur'aan Majeed and any other form of Thikr, and performing Nafl Salaat, and reciting the Athaan in a new and even in an old house. But to fabricate a custom which culminates in merrymaking is baseless. When moving into a new house, one may recite the Qur'aan Shareef, especially Surah Baqarah; perform some Nafl Salaat and make dua for aafiyat (safety and protection). But it is not permissible to invite people for a fabricated party/ custom which has no Sunnah origin and significance. The Athaan may also be recited in all the rooms.