Some £4.36 million of the unpaid tax stems from Rodriguez selling his image rights to Portuguese agent Jorge Mendes in December 2014.
El Mundo also goes on to state that the two-time Champions League winner made the sale in Casablanca, Morocco – where Madrid were playing in the Fifa Club World Cup.
The sale was made with Rodriguez listed as a non-resident in Spain, meaning he avoided the full amount of tax that would have been required of a Spanish resident.
Officials point to Rodriguez living in Spain for 183 days in 2014 and his finances being based in the country as legal proof he should have been registered as a Spanish resident. This has led to the amount payable by the former Monaco and Porto ace rise to £10.3 million through added sanctions and interest.