How to calculate self assessed taxes without registration status on a supplier?

We have a client requirement where, the self assessed taxes only need to be calculated on goods received from outside the country, for which we have already created geography rule where country is equal to France then Bill-from party is considered and where country is not equal to France then Bill-to party is considered. But this does not trigger self assessment taxes. We do not prefer Registration status as the client does not maintain the same for each supplier. Please suggest.

Thanks and regards,

Miti Shah