Spanish prosecutors have asked a judge to charge Radamel Falcao with defrauding Spain's tax authority of €5.66 million from 2012-13.
Meanwhile, prosecutors also accused Real Madrid defender Fabio Coentrao of trying to defraud almost €1.29m in 2011.
Falcao was accused of gaining illegal fiscal benefits and evading taxes for his image rights after signing for Atletico Madrid in 2011. The striker stayed for two seasons before moving to Monaco in 2013.
Both players tried to hide money in corporations in other other countries, the prosecution claims.
Last year, Barcelona's Lionel Messi and his father were sentenced to 21 months in prison for tax fraud. They were not sent to jail because sentences of less than two years for first offences are usually suspended in Spain.
In December, a prosecutor filed tax charges against Xabi Alonso, Angel Di Maria and Ricardo Carvalho, all former Real Madrid players.
Information from The Associated Press was used in this report.