Netflix Inc. is bringing its crackdown on account sharing to the US.

The service on Tuesday outlined procedures and costs for US customers who wish to continue sharing their accounts with people outside their household.

The streaming TV leader is sending emails to customers who share their passwords, according to a blog post by the company. Netflix is giving them the option to share their account for an additional $8 a month. The option is only available to customers of its $15.50 standard plan and its $20-a-month premium version.

The crackdown on password sharing, which began last year in Latin America, is a key part of Netflix’s strategy to generate more revenue from users. The company has said as many as 100 million households globally use an account they don’t pay for, including 30 million in the US and Canada.

Subscribers can still watch programs on mobile devices when they’re traveling. People who aren’t paying for an account and are just using a friend’s password will ultimately be cut off.

Greg Peters, Netflix’s co-chief executive officer, told investors last month that the password sharing crackdown is very much like a price increase in terms of customer reaction. Some people initially cancel, but ultimately subscriptions and revenue rise.

“That’s a really strong confirmation that we’ve got an approach that we can apply in many different countries with different market characteristics, including our largest revenue countries,” Peters said on an earnings call.

Netflix introduced a $7-a-month plan with ads in November in another effort to boost sales and subscriptions.

Shares of Netflix fell as much as 2.4% to $354.31 in New York. The stock was up 23% this year through the close Monday.

(Updates with details on plan starting in)