Regulations state that any one person is allowed to carry $10,000 without notifying customs and anything over that limit must be declared using the correct forms.
Cristiano Ronaldo’s mother was more than four times over the limit as she was caught carrying $55,000 (£43,000) in total.
Unable to prove the origin of the money, all but $10,000 was confiscated from her possession, as regulations allow, before she was allowed to board her flight back to her homeland.
A spokesman from the Civil Guard in Madrid is quoted saying by Eurosport: "This woman was stopped and money she was carrying taken and handed over to the Spanish tax authorities along with a report filed by the Civil Guard.”
The mother-of-four was on her way to Portugal when stopped by Civil Guard officers who went on to find the lucrative amount of money in her hand luggage.
If Aveiro cannot prove the origin of the money then she will be hit with a fine that she will have to pay in order to recover the remaining funds that were taken from her.
The regulations that saw the money taken from Aveiro to stop money laundering, the 61-year-old might not have been aware of when attempting to board the plane with the $55,000.