GoKawiilPlatforms like YouTube, Instagram and TikTok will need to take action to deal with scam adverts, under new proposals from Ofcom.
The regulator has published draft measures it says big tech should take to protect people from falling victim to fraudulent ads online - along with a list of services which will face more responsibilities under the Online Safety Act (OSA).
It says more than half of UK adults have come across potentially fraudulent ads online, with over a third seeing them often.
If the draft measures pass into law, firms which fail to comply could be made to pay £18m or 10% of global turnover - whichever is greater.
"For too long, victims have been exposed to scam ads online with tech giants simply not doing enough to combat the fraudsters using their platforms," said Ofcom online safety director Oliver Griffiths.
"We expect firms to take robust action to stamp out scam ads and boot out the bad actors behind them to safeguard their users."
Ofcom's proposed measures are targeting content which advertises products or services in a way that misleads or tricks viewers.
It said this includes mandating tech firms ban those who post scams and prevent them from creating new accounts, as well as those who impersonate real businesses.
"Platforms should not drag their heels – they can start making improvements for their users now," Griffiths said.
"And sites and apps that fail to meet their legal duties, once in force, can expect to face serious consequences."