Hi all,

I've sucessfully done a modification in account.tax model / amount_type field by adding 'weight' a new select value as follow:

from odoo import fields, models


class AccountTax(models.Model):
    _inherit = "account.tax"
    amount_type = fields.Selection(default='percent', string="Tax Computation", required=True,
            selection=[('group', 'Group of Taxes'), ('fixed', 'Fixed'), ('weight', 'Product weight based'), ('percent', 'Percentage of Price'), ('division', 'Percentage of Price Tax Included')],
            help="""
        - Group of Taxes: The tax is a set of sub taxes.
        - Fixed: The tax amount stays the same whatever the price.
        - Product weight based: Fixed amount per Kg.
        - Percentage of Price: The tax amount is a % of the price:
            e.g 100 * (1 + 10%) = 110 (not price included)
            e.g 110 / (1 + 10%) = 100 (price included)
        - Percentage of Price Tax Included: The tax amount is a division of the price:
            e.g 180 / (1 - 10%) = 200 (not price included)
            e.g 200 * (1 - 10%) = 180 (price included)
            """)

The issue comes when I try to  change amount field behaviuor in account.view_tax_form view's ID

This is view_tax_form record from odoo/addons/account/views/account_tax_views.xml:

<record id="view_tax_form" model="ir.ui.view">
    <field name="name">account.tax.formfield>
    <field name="model">account.taxfield>
    <field name="arch" type="xml">
        <form string="Account Tax">
            <sheet>
            <group>
                <group>
                    <field name="name"/>
                    <field name="amount_type"/>
                    <field name="active" widget="boolean_toggle"/>
                group>
                <group>
                    <field name="type_tax_use"/>
                    <field name="tax_scope"/>
                    <label for="amount" attrs="{'invisible':[('amount_type','not in', ('fixed', 'percent', 'division'))]}"/>
                    <div attrs="{'invisible':[('amount_type','not in', ('fixed', 'percent', 'division'))]}">
                        <field name="amount" class="oe_inline" nolabel="1"/>
                        <span class="o_form_label oe_inline" attrs="{'invisible':[('amount_type','=','fixed')]}">%span>
                    div>
                group>
            group>

I pretend to show field amount and change % per KG span tag when weight value is selected.

I've been done many attempts and google research but unfortunately I haven't found anything when extra html tags get in place.

Many thanks for your help!