Lionel Messi has this month been summoned to a court in Gava, near Barcelona, along with his father Jorge, to answer charges that between them they have defrauded the Spanish state of around 4 million euros. The prosecutor made an official complaint against them on 12 June and this current court hearing is to find out whether the state has grounds to bring criminal proceedings against him. If they did so and he was found guilty a jail sentence is possible, but things have a long way to go before they reach that point.
In the meantime, a more recent story is that Leo Messi has now paid back 10 million euros - which is more than he was accused of failing to pay in the first place, so you wonder where that figure comes from. The story is new and hasn't been confirmed yet, but you can get the details here.