Harry Potter actor Rupert Grint, who has an estimated net worth of $A65 million, has lost a legal battle to secure a massive tax refund.

According to The Guardian, a tax tribunal rejected the Grint’s appeal against a UK tax, payments and customs authority block on him avoiding a higher tax rate.

Grint, who played Ron Weasley in the super successful film versions of JK Rowling’s bestselling books, has earned an estimated £24 million from the franchise.

The 27-year-old was hoping 20 months of income could be taxed in the year 2009-2010 before the top rate of tax was raised from 40 to 50 per cent in 2010-2011.

This would have allowed Grint to save 10 per cent of his earnings, which would have equated to roughly £1 million (or $A1.68 million) according to his lawyers.

Rupert Grint in the first Harry Potter film, released in 2001.

The tribunal rejected his appeal on the grounds he had failed to meet the criteria required for changing his accounting dates.

Grint’s barrister was keen to point out his client’s case was not an attempt to avoid taxation but rather to save some of his earnings under a lower rate.

“There is no tax avoidance involved here,” lawyer Patrick Soares said, according to Metro UK.

“He has paid all his tax up front. If he wins the case he gets a refund. He just wants to make that point in open court.”

During Grint’s hearing, the actor admitted he had a “limited” knowledge of financial affairs and left the management of his fortune up to his father and his accountant.