Falcao is suspected of failing to correctly declare 5.6 million euros of income earned from image rights between 2012 and 2013 while he was at Atletico Madrid.
The 31-year-old will be able to reclaim the sum if he is eventually cleared, the source told AFP of the payment which includes interest on the original amount.
He is suspected of using a web of shell companies in the British Virgin Islands, Ireland, Colombia and Panama to avoid taxes on income from image rights.
Falcao has not denied the existence of these companies but has said he had nothing to pay for 2013, arguing that he was no longer resident in Spain and so no longer owed any tax there.
He has been accused of moving his tax residence to Monaco in order to escape the attentions of the Spanish taxman, before completing his transfer to the principality club in May of that year.
The player’s agent Jorge Mendes denied helping create shell companies for his clients when questioned by a Spanish court last month.
Mendes, a former nightclub manager, found himself in the eye of the storm last year in the “Football Leaks” media investigation into alleged corruption in the game.
Based on millions of documents, the investigation claims he offered his clients ways to avoid paying taxes on some of the money they earned.
Mendes’ highest-profile client is Real Madrid and Portugal forward Cristiano Ronaldo, who will go before a judge later this month to answer four counts of tax evasion of 14.7 million euros.
Barcelona’s Argentine forward Lionel Messi last week had a suspended prison term reduced to a heavy fine after he was convicted of hiding image rights royalties in offshore accounts.
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