US tennis star Andre Agassi has lost his legal battle to avoid paying UK income tax on endorsement deals.
Andre Agassi challenged a tax assessment for the 1998/99 season
Law Lords ruled he must pay tax on a portion of cash paid to him by Nike and Head because he endorsed their products at Wimbledon and other UK tournaments.
The Court of Appeal had earlier ruled Agassi was exempt because neither he nor the sports companies were UK-based.
But the Law Lords ruled foreign entertainers touring Britain must pay tax on money earned from such deals.
The Revenue feared that, had it lost its appeal, it would have been liable to repay millions of pounds to entertainers and sports stars who had toured the UK since 1988.
That was the year the Income and Corporations Taxes Act, which covers such deals, came into force.
The fact Nike and Head were paying money to the tennis star's US-based company, Agassi Enterprises Inc - rather than to Agassi himself - made no difference, the Law Lords ruled.
"Payments to foreign companies controlled by them are to be treated as payments to them," Lord Scott said.
Otherwise, payments of the tax would be rendered "to all intents voluntary", he added.
Lord Mance said there was "no incongruity" in entertainers or sportsmen being charged tax on money earned for endorsing products in the UK.
Agassi brought the case after challenging an assessment of £27,500 for the 1998/99 season.