account_move.xml

<?xml version="1.0" ?>
<odoo>

    <record id="account_move_form_discount_date" model="ir.ui.view">
        <field name="name">account.move.form.discount.date</field>
        <field name="model">account.move</field>
        <field name="inherit_id" ref="account.view_move_form" />
        <field name="arch" type="xml">
            <field name="partner_id" position="after">
                <field name="valid_discount_date" invisible="1" />
            </field>
        </field>
    </record>

    <record id="account_move_search_discount_date" model="ir.ui.view">
        <field name="name">account.move.search.discount.date</field>
        <field name="model">account.move</field>
        <field name="inherit_id" ref="account.view_account_invoice_filter" />
        <field name="arch" type="xml">
            <xpath expr="//filter[@name='late']" position="after">
                <filter
                    string="Discount Invoice"
                    name="valid_discount_dates"
                    domain="[('state', '=', 'open'), ('valid_discount_date', '&gt;',  (context_today()-datetime.timedelta(days=1)).strftime('%%Y-%%m-%%d'))]"
                    help="Filter invoices with early payment discounts"
                />
            </xpath>
        </field>
    </record>

</odoo>