hr_expense_sheet - Expense Sheet Extension for Odoo

Overview

This module extends Odoo's native HR Expense functionality with additional features for managing expense sheets.

Features

1. Tax-Included Expense Calculation

Problem: When creating an expense without a product, users often need to enter a total amount that already includes tax (common in Vietnam and other countries). However, Odoo's default behavior calculates tax on top of the base amount, not backward from the total.

Solution: This module calculates tax backward from the total when:

• No product is selected (user enters amount directly)
• User enters total_amount_currency as the total including tax
• A tax is selected

Example:

• User enters: total_amount_currency = 500,000 VND (total including tax)
• User selects: 10% VAT
• System calculates:
  • Untaxed amount = 500,000 / 1.1 = 454,545 VND
  • Tax amount = 500,000 - 454,545 = 45,455 VND

2. Expense Sheet Management

• Submit expenses for approval
• Approve/Refuse expenses
• Post journal entries
• Register payments
• View all expenses in a sheet

Installation

1. Copy this module to your Odoo addons directory
2. Update apps list
3. Search for "hr_expense_sheet" and install

Usage

Creating an Expense with Tax-Included Total

1. Go to Expenses > Expense Sheets
2. Create a new expense sheet
3. Add a new expense line
4. Leave Product empty (important!)
5. Enter the Total (Currency) amount (e.g., 500,000 VND)
6. Select a tax (e.g., 10% VAT)
7. The system automatically calculates:
   • Tax Amount: ~45,455 VND (calculated backward)
   • Total: 500,000 VND

Multiple Taxes

The module supports multiple tax selection. The tax rate is calculated as the sum of all selected tax percentages:

• Example: 10% VAT + 5% other tax = 15% total rate
• Formula: untaxed = total / 1.15

Technical Details

Modified Files

1. models/hr_expense.py

   • Extended hr.expense model
   • Added _compute_total_amount() method for backward tax calculation
   • Added _compute_total_amount_currency() to preserve user input

2. views/hr_expense_sheet_views.xml

   • Added form view for expense line with:
     • Hidden currency fields: currency_id, company_currency_id, is_multiple_currency
     • User-editable total_amount_currency field
     • Readonly tax_amount and total_amount fields

Key Methods

_compute_total_amount()

@api.depends('total_amount_currency', 'tax_ids', 'currency_id', 'company_id')
def _compute_total_amount(self):
    """Calculate tax backward from tax-included total."""
    for expense in self:
        if not expense.product_id and expense.total_amount_currency and expense.tax_ids:
            tax_rate = sum(tax.amount for tax in expense.tax_ids) / 100.0
            if tax_rate > 0:
                total_excluded = expense.total_amount_currency / (1 + tax_rate)
                tax_amount = expense.total_amount_currency - total_excluded
                expense.tax_amount = tax_amount
                expense.untaxed_amount = total_excluded
            expense.total_amount = expense.total_amount_currency

_compute_total_amount_currency()

@api.depends('quantity', 'price_unit', 'tax_ids', 'product_id')
def _compute_total_amount_currency(self):
    """Preserve user-entered total when no product is selected."""
    for expense in self:
        if not expense.product_id and expense.total_amount_currency:
            continue  # Don't recalculate - keep user's input
        super(HrExpense, expense)._compute_total_amount_currency()

XML View Changes

<!-- Hidden currency fields -->
<field name="currency_id" invisible="1"/>
<field name="company_currency_id" invisible="1"/>
<field name="is_multiple_currency" invisible="1"/>

<!-- User enters total (including tax) -->
<field name="total_amount_currency" widget="monetary" options="{'currency_field': 'currency_id'}"/>

<!-- Tax selection -->
<field name="tax_ids" widget="many2many_tags"/>

<!-- Calculated values (readonly) -->
<field name="tax_amount" readonly="1"/>
<field name="total_amount" readonly="1" widget="monetary" options="{'currency_field': 'company_currency_id'}"/>

Limitations

• Simple percentage taxes only: The backward calculation uses total / (1 + tax_rate) which works for single or multiple percentage taxes on the same base
• Compound taxes: Not fully supported (tax-on-tax scenarios)
• Fixed amount taxes: Not supported in backward calculation

Compatibility

• Odoo 19.0
• PostgreSQL database

License

See LICENSE file for full copyright and licensing details (Odoo MIT License).

Author

Custom module for Vietnamese localization with tax-included expense handling.