BRUSSELS, Sept 10 (Reuters) - Meta Platforms ( META )

and TikTok on Wednesday won their legal fight against a European

Union supervisory fee imposed on them under landmark tech rules,

after Europe's second-highest court faulted EU regulators on the

way they calculated the levy.

Meta and ByteDance's TikTok sued the European Commission

after they were hit with a supervisory fee of 0.05% of their

annual worldwide net income to cover the EU executive's cost of

monitoring their compliance with the Digital Services Act.

The size of the annual fee is tied to the number of average

monthly active users for each company and whether each posts a

profit or loss in the preceding financial year. The two

companies said the methodology was flawed, resulting in

disproportionate fees.

The Luxembourg-based General Court sided with Meta and

TikTok, giving EU regulators 12 months to fix their methodology

using a different legal act.

"That methodology... should have been adopted not in the

context of implementing decisions but in a delegated act, in

accordance with the rules laid down in the DSA," judges said.

They said regulators need not repay the 2023 fees paid by

the companies for now, while they come up with a new legal basis

for the methodology used to determine the size of the fee.

The DSA, which entered into force in November 2022, requires

very large online platforms to do more to tackle illegal and

harmful content on their sites or risk fines as much as 6% of

their annual global turnover.

Other companies required to pay the supervisory fee include

Amazon ( AMZN ), Apple ( AAPL ), Booking.com, Google

, Microsoft ( MSFT ), Elon Musk's X social media

platform, Snapchat and Pinterest ( PINS ).

The cases are T-55/24 - Meta Platforms Ireland v Commission

and T-58/24 - TikTok Technology v Commission.