However, neither is likely to spend any time behind bars as, under Spanish law, prison sentences of less than two years can be served under probation.
In addition to the prison sentences, Lionel Messi was fined around €2m (£1.72bn, $2.2bn) and his father €1.5m for using tax havens in Belize and Uruguay to conceal earnings from image rights.
They were found guilty of resorting to fictitious companies to evade Spanish taxes on income from companies using Lionel Messi’s image rights.
Both made a voluntary €5m “corrective payment” in August 2013, which was equal to the value of the unpaid tax plus interest.
Lionel Messi has always denied knowing what was happening with his finances, which were being managed in part by his father, and the footballer appeared in court on 20 April to appeal the jail sentence.
However, the High Court in Barcelona ruled in June 2015 that not knowing about his finances did not mean that Messi should be granted impunity.
But in its decision on Wednesday, the court said: “It defies logic to concede that someone who earns a large income does not know that he must pay taxes on it.”
Jorge Messi’s jail term was reduced from 21 months to 15 by the Supreme Court to take into account the money he had since handed to the tax authorities.
Tax efficient structures
Miles Dean, founding partner of Milestone International Tax Consultants, said: “Messi’s case highlights the importance of structuring image rights arrangements properly.
“There is no doubt that a player such as Messi has extremely valuable image rights and that it is possible to structure their exploitation in a tax efficient manner.
“However, one might argue that he earns so much from his Barcelona salary that there is no need to go to the lengths that he and his father did to deprive the tax authorities.
“Lest we forget that Spain is bankrupt and the rule of law isn’t adhered to in the same was as say the UK – one could equally argue that he’s been made an example of.
“The lesson here is not to risk pushing boundaries and to always seek professional advice.”