l10n_it_vat_registries/security/vat_registry_security.xml
<?xml version="1.0" encoding="utf-8"?>
<openerp>
<data noupdate="1">
<record id="tax_registry_comp_rule" model="ir.rule">
<field name="name">tax_registry multi-company</field>
<field name="model_id" ref="model_account_tax_registry"/>
<field name="global" eval="True"/>
<field name="domain_force">['|',('company_id','=',False),('company_id','child_of',[user.company_id.id])]</field>
</record>
</data>
</openerp>