The Netflix password-sharing ban has come into force for UK customers.
The clampdown first hit Canada and Spain earlier this year, but customers in the UK who share passwords will be getting an email today explaining an account is only for "one household".
Customers can add someone from outside their house for £4.99 a month.
Netflix has confirmed that customers will not automatically be charged the £4.99 if there is a member outside their household. Customers will have to opt-in for it.
Those in the household can still use Netflix wherever they are, including on holiday or on the go.
Previously, Netflix subscribers were told they were not supposed to share their passwords with people outside their households.
However, this didn't stop users from giving their account details to friends and family so they can save cash.
In a statement, Netflix said: "Starting today, we will be sending this email to members who are sharing Netflix outside their household in the United Kingdom.
"A Netflix account is for use by one household. Everyone living in that household can use Netflix wherever they are – at home, on the go, on holiday – and take advantage of new features like Transfer Profile and Manage Access and Devices.
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"We recognise that our members have many entertainment choices. It’s why we continue to invest heavily in a wide variety of new films and TV programmes – so whatever your taste, mood or language and whoever you’re watching with, there’s always something satisfying to watch on Netflix."
Netflix first confirmed plans to “monetize” paid-for account sharing globally in a letter to shareholders in October 2022.
The subscription service introduced fees for password sharing in Canada, New Zealand, Portugal and Spain in March.
Canadian subscribers can add an extra member as a "sub-account" for CAD$7.99 (£4.78) and in New Zealand the charge is NZ$7.99 (£3.97).
Portugal subscribers can add a "sub-account" for €3.99 (£3.51) while Spain customers must spend €5.99 (£5.27).
In April, the company confirmed an additional 1.75 million subscribers signed up to its service during the first quarter of 2023.
This means the total number of subscribers now stands at 232.5 million - up 4.9 per cent from the final three months of 2022.
In April Netflix has also announced it will end its DVD-by-mail business after 25 years, with its last discs to be posted out on September 29.
