Lawyers acting for former King Juan Carlos are attempting to settle the financial situation in connection with the ongoing investigation into the use of credit cards.
The investigation centres on the source of the funds which are reported as being from Mexican business magnate Allen Sanginés-Krause. The cards were used to pay for stays in hotels and trips between 2016 and 2018.
The dates of the investigation are important as the fomer king lost his immunity from prosecution once he abdicated in 2014.
The Spanish daily El Pais has reported that expenditure of around €500,000 was made in three tax years.
The paper reported that the tax investigation had already interviewed Sanginés-Krause as well as his Aide-de-Campe, Colonel Nicolas Murga Mendoza who is supposed to have made the payments with the credit cards on behalf of the former monarch.
Juan Carlos reigned from 1975 until 2014 and is credited with guiding the country through a peaceful transition to democracy and the restoration of democracy and consitutional monachy approved in the 1978 Constitution.
He abdicated in 2014 in favour of his son Felipe VI, following a string of scandals and left Spain earlier this year to live in the United Arab Emirates.