flectra/addons/account_budget/security/account_budget_security.xml

<?xml version="1.0" encoding="utf-8"?>
<flectra>
    <data noupdate="1">

        <record id="budget_post_comp_rule" model="ir.rule">
            <field name="name">Budget post multi-company</field>
            <field name="model_id" ref="model_account_budget_post"/>
            <field eval="True" name="global"/>
            <field name="domain_force">['|',('company_id','=',False),('company_id','child_of',[user.company_id.id])]</field>
        </record>

        <record id="budget_comp_rule" model="ir.rule">
            <field name="name">Budget multi-company</field>
            <field name="model_id" ref="model_crossovered_budget"/>
            <field eval="True" name="global"/>
            <field name="domain_force">['|',('company_id','=',False),('company_id','child_of',[user.company_id.id])]</field>
        </record>

        <record id="budget_lines_comp_rule" model="ir.rule">
            <field name="name">Budget lines multi-company</field>
            <field name="model_id" ref="model_crossovered_budget_lines"/>
            <field eval="True" name="global"/>
            <field name="domain_force">['|',('company_id','=',False),('company_id','child_of',[user.company_id.id])]</field>
        </record>
        
        <record model="res.users" id="base.user_root">
            <field eval="[(4,ref('analytic.group_analytic_accounting'))]" name="groups_id"/>
        </record>

    </data>
</flectra>