English to French Law/Patents Law: Taxation & Customs service contract

This is a section dealing with taxes in a service contact between a service provider and the beneficiary of these services.

I am unsure whether I should user 'imposer' or 'prélever', and whether 'sur' would be the most appropriate preposition.

The wider context is :

'Service Recipient shall try it best to establish the applicability of indirect taxes (e.g., VAT, withholding taxes) to its invoices and credit notes and will charge indirect tax on invoices where it reasonably believes or is advised by the relevant tax authorities or its tax advisors that it is legally obliged to do so.'

Thank you for your help.