Harry Potter star Rupert Grint has crossed wands with tax officials.
An accountant who advises Rupert said the actor, who played Ron Weasley in the Harry Potter film series, could be in line for a refund of around £1 million if he won a fight with HM Revenue and Customs.
The dispute is being analysed by Judge Barbara Mosedale at a tax tribunal hearing in London which is due to end later this week.
Rupert, 27, was at the tribunal for the first day of the hearing on Monday and left without comment.
Accountant Dan Clay, who is based at Clay and Associates and advises the star, said the dispute related to the way accounts had been timetabled.
He said the actor and tax officials were in dispute over when an accounting year ended.
Mr Clay said the dispute related to accounts filed more than five years ago.
He said Rupert had paid all taxes due and would be in line for a refund of "just over £1 million" if he won.
A spokesman for HM Revenue and Customs said officials could not comment.