Spanish media report that the abdication of King Juan Carlos I will take effect on 18 June. Although the King signed his abdication on Monday, a bill must be passed by both houses of the Cortes (Parliament) for it to come into force. When the bill has been approved by both the Congress of Deputies and the Senate, it will be sanctioned by King Juan Carlos at the Royal Palace in Madrid on 18 June.
Prince Felipe will succeed to the throne as soon as the abdication act is published, and the following day he will be sworn in during a joint session of the Cortes, as his father was on 22 November 1975.
In 1975 the swearing in was followed by a mass in the Church of San Jeronimo five days later, but as a result of the secularisation of Spain this has now been dispensed with.
The 1975 enthronement mass was attended by several foreign heads of state and royals, which was important for King Juan Carlos, who came to the throne as the appointed successor of the Fascist dicator Francisco Franco, but intended to dismantle the dictatorship. This time no foreign heads of state or royals will be invited, which the royal household explains with lack of time and space in the Cortes.
It is as yet unknown what other members of the Spanish royal family, if any, will be present for the swearing in, but I would expect that at least the new Queen will join her husband and that their two daughters will also be present.
Curiously the media refer to the inauguration as a coronation and claim that Prince Felipe will be crowned. This is obviously wrong, as the swearing in is an entirely secular ceremony and no monarch has been crowned in Spain since the unification of the country in the fifteenth century.