Hey there @Ghaya77565 - great question!

There is not currently a way to make it so some people have to pay while others do not on a single event type. You will want to create two identical event types - one that collects payments and one that does not. You can make the free event type “secret” and only share the link with those you’d like to allow to book for free, if you’d like. You can also use routing forms to properly route people to the free or paid event type. 

Routing forms let you request information such as industry, company size, specific interests, etc. from website visitors and automatically direct them to a specific scheduling or web page based on their responses. It's great for screening and qualifying sales leads on a website or matching clients or students to the booking page of the right subject-matter expert based on their interests, program, or other criteria. You can read more about setting up routing forms, here!

For example, if you are allowing anyone under 18 to book for free, you could: 

1. create a question on the routing form that asks invitees if they are over 18
2. create routing logic that sends “yes” answers to the paid event type and “no” answers to the free event type

This is just an example! =) 

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I hope this helps!