Spain's state prosecutor would swap jail time for a fine of €255,000 ($285,000; £224,000), which equates to €400 for each day behind bars.
The final decision on the fine rests in the hands of the Spanish courts.
Messi, along with his father Jorge, was found guilty of defrauding Spain of €4.1m between 2007 and 2009.
The court in Barcelona found they used tax havens in Belize and Uruguay.
As well as the jail terms, the Barcelona star and Argentina international was fined about €2m and his father €1.5m. They made a voluntary €5m "corrective payment", equal to the alleged unpaid tax plus interest, in August 2013.
Messi's appeal against the sentence was rejected by the Supreme Court last month, but his father's jail time was reduced because he paid some of the taxes.
However, Messi was never expected to serve time in jail, as under the Spanish system, prison terms of under two years can be served under probation.