+ my $conf = new FS::Conf;
+ return 'Tax exemption number required for '. $self->taxname. ' exemption'
+ if ! $self->exempt_number
+ && ( $conf->exists('tax-cust_exempt-groups-require_individual_nums')
+ || $conf->config('tax-cust_exempt-groups-num_req') eq 'all'
+ || ( $conf->config('tax-cust_exempt-groups-num_req') eq 'residential'
+ && ! $self->cust_main->company
+ )
+ );
+