[ADD] account_tax_product_amount: set tax amount per product variant

Author: petrus-v

account_tax_product_amount/README.rst

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+==========================
+Account tax product amount
+==========================
+
+.. 
+   !!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!
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+
+.. |badge1| image:: https://img.shields.io/badge/maturity-Beta-yellow.png
+    :target: https://odoo-community.org/page/development-status
+    :alt: Beta
+.. |badge2| image:: https://img.shields.io/badge/licence-LGPL--3-blue.png
+    :target: http://www.gnu.org/licenses/lgpl-3.0-standalone.html
+    :alt: License: LGPL-3
+.. |badge3| image:: https://img.shields.io/badge/github-OCA%2Faccount--fiscal--rule-lightgray.png?logo=github
+    :target: https://github.com/OCA/account-fiscal-rule/tree/18.0/account_tax_product_amount
+    :alt: OCA/account-fiscal-rule
+.. |badge4| image:: https://img.shields.io/badge/weblate-Translate%20me-F47D42.png
+    :target: https://translation.odoo-community.org/projects/account-fiscal-rule-18-0/account-fiscal-rule-18-0-account_tax_product_amount
+    :alt: Translate me on Weblate
+.. |badge5| image:: https://img.shields.io/badge/runboat-Try%20me-875A7B.png
+    :target: https://runboat.odoo-community.org/builds?repo=OCA/account-fiscal-rule&target_branch=18.0
+    :alt: Try me on Runboat
+
+|badge1| |badge2| |badge3| |badge4| |badge5|
+
+This module allows you to manage fixed tax amounts that vary per product
+variant.
+
+By default, Odoo manages fixed tax amounts at the tax level. However,
+some taxes effectively depend on product characteristics (like
+dimensions, weight, or material) while sharing the same tax
+configuration (same account, same name, same tax report line).
+
+With this module, you can configure a tax with ``Amount Type`` set to
+``Fixed`` and enable the **Use Product Amount** option. This tells Odoo
+to look for the specific amount defined on the product variant. If no
+specific amount is found for the variant, the default amount defined on
+the tax is used.
+
+**Features:**
+
+- Define specific tax amounts per product variant.
+- Support for multiple taxes per product.
+- Multi-company support.
+- Compatible with Sales, Purchases, Invoicing, and Website Sales.
+
+..
+
+   **Note**: This module is particularly useful for handling
+   **Eco-taxes** (or similar levies) and offers advantages over other
+   community modules:
+
+   - Compared to ``account_ecotax``: This module relies on the standard
+     Odoo Tax engine. This makes it natively compatible with accounting,
+     invoicing, and reporting without needing glue modules for every
+     application (Sales, Purchase, POS, etc.). It also allows using
+     different accounts per tax easily.
+   - Compared to ``account_ecotax_tax``: This module does not rely on
+     ``account_tax_python`` (Python Code taxes), which can be complex to
+     maintain. It also supports multiple different tax amounts for a
+     single variant independently and offers better flexibility.
+
+**Table of contents**
+
+.. contents::
+   :local:
+
+Configuration
+=============
+
+To configure this module, you need to:
+
+1. **Configure Accounts**: Setup specific accounts for your taxes in
+   your Chart of Accounts, or decide which existing accounts to use.
+
+2. **Create a Tax**:
+
+   - Go to **Accounting > Configuration > Taxes**.
+   - Create a new tax.
+   - Set **Tax Computation** (Amount Type) to ``Fixed``.
+   - Check the box **Use Product Amount**.
+   - Set a default **Amount**. This will be used as a fallback if no
+     specific amount is set on the product variant.
+   - Configure other settings (Accounts, Tax Group, Label on Invoices,
+     etc.) as usual.
+
+3. **Add tax on product template**:
+
+   - Go to **Product template** form view.
+   - Select the product template.
+   - Add the tax to the **Sales/Purchase Taxes** field.
+   - Save the record this will generate the tax amount records for all
+     existing variants using the default tax amount.
+
+4. **Define Amounts on Products**:
+
+   - Go to the **Product Variant** form view.
+   - You will find a new tab or section (depending on view
+     configuration) to set the fixed amounts for each tax that has "Use
+     Product Amount" enabled.
+   - Alternatively, go to **Accounting > Configuration > Accounting >
+     Tax > Product Amounts** to see and manage all product tax amounts
+     in one place.
+
+**Eco-Tax Example (France)**
+
+In France, the "Éco-participation" (Eco-tax) is a fixed contribution
+added to the price of new items to fund recycling and waste management.
+The amount depends on the product's characteristics (weight, type,
+material).
+
+*Scenario*: You sell a sofa that contains electronic components (e.g., a
+massage sofa). This product is subject to two distinct eco-taxes: one
+for the furniture (Eco-mobilier) and one for the electronics (DEEE).
+
+1. **Purchase**: When you buy the goods, the eco-tax is billed by your
+   supplier. It is not recoverable VAT but an expense spread over the
+   product cost.
+
+   - We advise using a dedicated Expense Account (e.g., ``607...``) for
+     each tax or a generic one to track these costs.
+
+2. **Sale**: When you sell the product, you collect the eco-tax from the
+   customer.
+
+   - Use a dedicated Income Account (e.g., ``707...`` or a liability
+     account depending on your accounting rules) for the tax.
+   - Since the Eco-tax is part of the taxable basis for VAT, ensure that
+     the Eco-tax is applied *before* VAT.
+   - In the Tax configuration, for the VAT tax, ensure "Affect Base of
+     Subsequent Taxes" is checked (or simply ensure the Eco-tax is in a
+     Tax Group with lower sequence/sequence number so it applies first,
+     and VAT applies on top).
+
+*Calculation Example*:
+
+- Sofa Base Price: 10.00€
+- Eco-mobilier (Furniture Tax): 1.50€
+- VAT (20%): Applied on (10.00€ + 1.50€) = 11.50€ \* 20% = 2.30€
+- **Total Price**: 10.00€ + 1.50€ + 2.30€ = 13.80€
+
+*Journal Entries*:
+
+- **Credit** 707000 Product Sales: 10.00€
+- **Credit** 707100 Eco-tax Income (or similar): 1.50€
+- **Credit** 445700 Output VAT: 2.30€
+- **Debit** 411100 Customer Receivable: 13.80€
+
+Usage
+=====
+
+Once configured:
+
+1. Create a Sales Order, Purchase Order, or Invoice.
+2. Select a Product Variant that has a specific tax amount configured.
+3. Add the corresponding tax (the one with "Use Product Amount" checked)
+   to the line.
+
+..
+
+   **Note**: If the tax is set as a Default Tax on the product, it will
+   be added automatically.
+
+4. Odoo will compute the tax amount based on the value defined for the
+   selected variant.
+5. If you change the quantity, the fixed tax amount is multiplied by the
+   quantity (e.g., 2 units \* 1.50€ = 3.00€ tax).
+
+Known issues / Roadmap
+======================
+
+- Allow setting the tax amount directly from the **Product Template**
+  view when the product has only one variant.
+- Support for **Point of Sale (POS)** via a dedicated bridge module
+  (e.g., ``pos_account_tax_product_amount``).
+
+Bug Tracker
+===========
+
+Bugs are tracked on `GitHub Issues <https://github.com/OCA/account-fiscal-rule/issues>`_.
+In case of trouble, please check there if your issue has already been reported.
+If you spotted it first, help us to smash it by providing a detailed and welcomed
+`feedback <https://github.com/OCA/account-fiscal-rule/issues/new?body=module:%20account_tax_product_amount%0Aversion:%2018.0%0A%0A**Steps%20to%20reproduce**%0A-%20...%0A%0A**Current%20behavior**%0A%0A**Expected%20behavior**>`_.
+
+Do not contact contributors directly about support or help with technical issues.
+
+Credits
+=======
+
+Authors
+-------
+
+* Pierre Verkest
+
+Maintainers
+-----------
+
+This module is maintained by the OCA.
+
+.. image:: https://odoo-community.org/logo.png
+   :alt: Odoo Community Association
+   :target: https://odoo-community.org
+
+OCA, or the Odoo Community Association, is a nonprofit organization whose
+mission is to support the collaborative development of Odoo features and
+promote its widespread use.
+
+.. |maintainer-petrus-v| image:: https://github.com/petrus-v.png?size=40px
+    :target: https://github.com/petrus-v
+    :alt: petrus-v
+
+Current `maintainer <https://odoo-community.org/page/maintainer-role>`__:
+
+|maintainer-petrus-v| 
+
+This module is part of the `OCA/account-fiscal-rule <https://github.com/OCA/account-fiscal-rule/tree/18.0/account_tax_product_amount>`_ project on GitHub.
+
+You are welcome to contribute. To learn how please visit https://odoo-community.org/page/Contribute.

account_tax_product_amount/__init__.py

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+from . import models

account_tax_product_amount/__manifest__.py

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+# Copyright 2025 Pierre Verkest <[email protected]>
+# License LGPL-3.0 or later (http://www.gnu.org/licenses/lgpl.html).
+{
+    "name": "Account tax product amount",
+    "summary": "Manage tax amount per product variant",
+    "version": "18.0.1.0.0",
+    "category": "Accounting/Accounting",
+    "license": "LGPL-3",
+    "author": "Pierre Verkest, Odoo Community Association (OCA)",
+    "maintainers": ["petrus-v"],
+    "depends": ["account", "product"],
+    "data": [
+        "security/ir.model.access.csv",
+        "security/ir_rules.xml",
+        "views/account_tax_view.xml",
+        "views/account_tax_product_amount_view.xml",
+        "views/product_product_view.xml",
+    ],
+    "website": "https://github.com/OCA/account-fiscal-rule",
+}

account_tax_product_amount/i18n/account_tax_product_amount.pot

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+# Translation of Odoo Server.
+# This file contains the translation of the following modules:
+# 	* account_tax_product_amount
+#
+msgid ""
+msgstr ""
+"Project-Id-Version: Odoo Server 18.0\n"
+"Report-Msgid-Bugs-To: \n"
+"Last-Translator: \n"
+"Language-Team: \n"
+"MIME-Version: 1.0\n"
+"Content-Type: text/plain; charset=UTF-8\n"
+"Content-Transfer-Encoding: \n"
+"Plural-Forms: \n"
+
+#. module: account_tax_product_amount
+#: model:ir.model,name:account_tax_product_amount.model_account_tax_product_amount
+msgid "Account Tax Product Amounts (ie: usefull to manage ecotax)"
+msgstr ""
+
+#. module: account_tax_product_amount
+#: model:ir.model.fields,field_description:account_tax_product_amount.field_account_tax_product_amount__amount
+msgid "Amount"
+msgstr ""
+
+#. module: account_tax_product_amount
+#: model:ir.model.fields,field_description:account_tax_product_amount.field_account_tax_product_amount__company_id
+msgid "Company"
+msgstr ""
+
+#. module: account_tax_product_amount
+#: model_terms:ir.actions.act_window,help:account_tax_product_amount.action_tax_product_amount
+msgid "Create a new tax amount for a product variant"
+msgstr ""
+
+#. module: account_tax_product_amount
+#: model:ir.model.fields,field_description:account_tax_product_amount.field_account_tax_product_amount__create_uid
+msgid "Created by"
+msgstr ""
+
+#. module: account_tax_product_amount
+#: model:ir.model.fields,field_description:account_tax_product_amount.field_account_tax_product_amount__create_date
+msgid "Created on"
+msgstr ""
+
+#. module: account_tax_product_amount
+#: model:ir.model.fields,help:account_tax_product_amount.field_product_product__tax_amount_ids
+msgid "Define specific tax fixed amounts for this variant."
+msgstr ""
+
+#. module: account_tax_product_amount
+#: model:ir.model.fields,help:account_tax_product_amount.field_account_tax_product_amount__type_tax_use
+msgid ""
+"Determines where the tax is selectable. Note: 'None' means a tax can't be "
+"used by itself, however it can still be used in a group. 'adjustment' is "
+"used to perform tax adjustment."
+msgstr ""
+
+#. module: account_tax_product_amount
+#: model:ir.model.fields,field_description:account_tax_product_amount.field_account_tax_product_amount__display_name
+msgid "Display Name"
+msgstr ""
+
+#. module: account_tax_product_amount
+#: model_terms:ir.ui.view,arch_db:account_tax_product_amount.product_normal_form_view
+msgid "Fixed Tax Amount"
+msgstr ""
+
+#. module: account_tax_product_amount
+#: model:ir.model.fields,field_description:account_tax_product_amount.field_account_tax_product_amount__id
+msgid "ID"
+msgstr ""
+
+#. module: account_tax_product_amount
+#: model:ir.model.fields,help:account_tax_product_amount.field_account_tax__use_product_amount
+msgid ""
+"If checked, the tax amount is taken from the product variant (with a "
+"fallback to the tax amount)."
+msgstr ""
+
+#. module: account_tax_product_amount
+#: model:ir.model.fields,field_description:account_tax_product_amount.field_account_tax_product_amount__write_uid
+msgid "Last Updated by"
+msgstr ""
+
+#. module: account_tax_product_amount
+#: model:ir.model.fields,field_description:account_tax_product_amount.field_account_tax_product_amount__write_date
+msgid "Last Updated on"
+msgstr ""
+
+#. module: account_tax_product_amount
+#: model:ir.model,name:account_tax_product_amount.model_product_template
+msgid "Product"
+msgstr ""
+
+#. module: account_tax_product_amount
+#: model:ir.model,name:account_tax_product_amount.model_product_product
+#: model:ir.model.fields,field_description:account_tax_product_amount.field_account_tax_product_amount__product_id
+msgid "Product Variant"
+msgstr ""
+
+#. module: account_tax_product_amount
+#: model:ir.model,name:account_tax_product_amount.model_account_tax
+#: model:ir.model.fields,field_description:account_tax_product_amount.field_account_tax_product_amount__tax_id
+msgid "Tax"
+msgstr ""
+
+#. module: account_tax_product_amount
+#: model:ir.actions.act_window,name:account_tax_product_amount.action_tax_product_amount
+#: model:ir.ui.menu,name:account_tax_product_amount.menu_tax_product_amount
+msgid "Tax Product Amount"
+msgstr ""
+
+#. module: account_tax_product_amount
+#: model:ir.model.fields,field_description:account_tax_product_amount.field_account_tax_product_amount__type_tax_use
+msgid "Tax Type"
+msgstr ""
+
+#. module: account_tax_product_amount
+#: model:ir.model.fields,field_description:account_tax_product_amount.field_product_product__tax_amount_ids
+msgid "Tax fixed amounts"
+msgstr ""
+
+#. module: account_tax_product_amount
+#: model:ir.model.constraint,message:account_tax_product_amount.constraint_account_tax_product_amount_product_tax_unique
+msgid "The tax amount must be unique per product variant and tax."
+msgstr ""
+
+#. module: account_tax_product_amount
+#: model_terms:ir.ui.view,arch_db:account_tax_product_amount.product_normal_form_view
+#: model_terms:ir.ui.view,arch_db:account_tax_product_amount.product_variant_easy_edit_view
+msgid ""
+"To add / remove tax amount line, please use\n"
+"                        Sales/Purchase Taxes field on product template."
+msgstr ""
+
+#. module: account_tax_product_amount
+#: model:ir.model.fields,field_description:account_tax_product_amount.field_account_tax__use_product_amount
+msgid "Use Product Amount"
+msgstr ""