[ADD] accounting: How to manage cash basis taxes

https://docs.google.com/document/d/196GaaOFSL__OG3BQFteUGjuSqXcl_-95YonVLPXtmJc/edit

accounting/others/taxes.rst

@@ -12,3 +12,4 @@ Taxes
    taxes/tax_included
    taxes/retention
    taxes/B2B_B2C
+   taxes/cash_basis_taxes

accounting/others/taxes/cash_basis_taxes.rst

@@ -0,0 +1,87 @@
+==============================
+How to manage cash basis taxes
+==============================
+
+The cash basis taxes are due when the payment has been done and not at
+the validation of the invoice (as it is the case with standard taxes).
+Reporting your income and expenses to the administration based on the
+cash basis method is legal in some countries and under some conditions.
+
+Example : You sell a product in the 1st quarter of your fiscal year and
+receive the payment the 2nd quarter of your fiscal year. Based on the
+cash basis method, the tax you have to pay to the administration is due
+for the 2nd quarter.
+
+How to configure cash basis taxes ? 
+------------------------------------
+
+You first have to activate the setting in
+:menuselection:`Accounting --> Configuration --> Settings --> Allow Tax Cash Basis`.
+You will be asked to define the Tax Cash Basis Journal.
+
+.. image:: media/cash_basis_taxes01.png
+    :width: 5.04688in
+    :height: 0.79688in
+    :align: center
+
+Once this is done, you can configure your taxes in
+:menuselection:`Accounting --> Configuration --> Taxes`.
+You can open a tax and in the *Advanced Options*
+tab you will see the checkbox *Use Cash Basis*. You will then have to
+define the *Tax Received Account*.
+
+.. image:: media/cash_basis_taxes02.png
+    :width: 6.50000in
+    :height: 1.81944in
+    :align: center
+
+What is the impact of cash basis taxes in my accounting ? 
+----------------------------------------------------------
+
+Let’s take an example. You make a sale of $100 with a 15% cash basis
+tax. When you validate the customer invoice, the following entry is
+created in your accounting:
+
++-----------------------------+-----------------------+
+| Customer Invoices Journal   |                       |
++=============================+=======================+
+| **Debit**                   | **Credit**            |
++-----------------------------+-----------------------+
+| Receivables $115            |                       |
++-----------------------------+-----------------------+
+|                             | Tax Account $15       |
++-----------------------------+-----------------------+
+|                             | Income Account $100   |
++-----------------------------+-----------------------+
+
+A few days later, you receive the payment:
+
++----------------+--------------------+
+| Bank Journal   |                    |
++================+====================+
+| **Debit**      | **Credit**         |
++----------------+--------------------+
+| Bank $115      |                    |
++----------------+--------------------+
+|                | Receivables $115   |
++----------------+--------------------+
+
+When you reconcile the invoice and the payment, this entry is generated:
+
++--------------------------+----------------------------+
+| Tax Cash Basis Journal                                |
++==========================+============================+
+| **Debit**                | **Credit**                 |
++--------------------------+----------------------------+
+| Tax Account $15          |                            |
++--------------------------+----------------------------+
+|                          | Tax Received Account $15   |
++--------------------------+----------------------------+
+| Income Account $100      |                            |
++--------------------------+----------------------------+
+|                          | Income Account $100        |
++--------------------------+----------------------------+
+
+.. tip::
+    The two journal items created in the Income Account are neutral but
+    they are needed to insure correct tax reports in Odoo.