Can we use Google Workspace Gmail at the same time with our on premise mail server?

[Charitos]

Hello admins!

We have an onpremise mail server and want to migrate to Google Workspace gradually. At first stage we want some users to use the Google Workspace Gmail for senting & receiving emails and the other ones will use the current mail server.

Is there a way to do that or do we have to transfer and use all the mail accounts under our domain from day one? If that's possible do we have to pay licences for all the email accounts we have at our company?

Thank you in advance.