Combine online payments with payments per invoice

[Leendepauw]

Hello everyone!

I am building a shop that will be available for both professional and private customers. Private customers will always pay directly via the mobile application we installed. 

But often professional customers want to buy and receive an invoice which they pay afterwards. 

Is there a way to activate manual payment (invoice = automatically sent) for professional customers? 

I have already added a field in the account registration where they indicate professional or private. Maybe I can generate a tag for that specific customer based on the answer in the registration and this way we could activate that manual payment only for professional customers? 

I am not really looking for an app because of costs, so let's see if there's a workaround. 

Many thanks for thinking along!