Olivian Group Invoicing System

A comprehensive PHP-based invoicing and quotation management system with tax handling, client management, and professional invoice generation.

Features

• Invoice Management: Create, edit, view, and delete invoices with tax calculations
• Quotation Management: Generate quotations that can be converted to invoices
• Tax Handling:
  • Configurable tax rates per document
  • Tax-exempt item support for individual line items
  • Proper tax calculation on taxable items only
• Client Management: Maintain client information and contact details
• Professional Printing: Generate print-ready invoices and quotations
• Dashboard Overview: Quick access to key metrics and recent documents
• Settings Management: Configure company information and default tax rates

Tech Stack

• Backend: PHP 8.2.12
• Database: MySQL/MariaDB
• Frontend: Bootstrap 5.1.3, jQuery 3.6.0, DataTables 1.11.5
• Server: Apache 2.4.58
• Version Control: Git

Prerequisites

• PHP 8.0+
• MySQL 5.7+
• Apache with .htaccess support
• Composer 2.0+

Installation

1. Clone the Repository

git clone https://github.com/Varence-kiiru/Invoicing-system.git
cd Invoicing-system

2. Install Dependencies

composer install

3. Configure Environment

Copy the example environment file and update with your database credentials:

cp .env.example .env

Edit .env with your configuration:

APP_ENV=development
DB_HOST=localhost
DB_NAME=olivian_invoice
DB_USER=root
DB_PASS=your_password

4. Create Database

mysql -u root -p < database/olivian_invoice.sql

Replace root with your MySQL username and enter your password when prompted.

5. Set Up Web Server

For Apache/XAMPP, ensure the project is in htdocs:

C:\xampp\htdocs\Invoicing-system

Or configure your virtual host to point to the project directory.

6. Access the Application

Open your browser and navigate to:

http://localhost/Invoicing-system

Database Schema

Tables

• settings - Company configuration (name, address, tax rate, logo, etc.)
• clients - Client information (name, email, phone, address)
• invoices - Invoice records with totals and payment status
• invoice_items - Line items for invoices with tax-exempt flags
• quotations - Quotation records with validity dates
• quotation_items - Line items for quotations with tax-exempt flags

Key Features

• Foreign key relationships with CASCADE delete
• Tax rate stored per invoice/quotation (preserves historical accuracy)
• Tax-exempt flag per item (allows mixed taxable/non-taxable items)
• Timestamp tracking on client creation

Usage

Creating an Invoice

1. Navigate to Invoices menu
2. Click New Invoice button
3. Select client and add items
4. Mark items as tax-exempt if needed
5. Adjust tax rate if different from default
6. Click Save Invoice

Creating a Quotation

1. Navigate to Quotations menu
2. Click New Quotation button
3. Add quotation items
4. Review calculated totals
5. Save and share with client

Converting Quotation to Invoice

1. View the quotation
2. Click Convert to Invoice
3. Quotation becomes an invoice with same details

Tax Calculations

• Taxable Subtotal: Sum of all non-exempt items
• Non-Taxable Subtotal: Sum of items marked as tax-exempt
• Tax Amount: Taxable subtotal × (tax rate / 100)
• Final Total: Subtotal + Tax Amount

Project Structure

├── ajax/                    # AJAX endpoints for dynamic operations
│   ├── save_invoice.php
│   ├── get_invoice.php
│   ├── delete_invoice.php
│   ├── save_quotation.php
│   ├── get_quotation.php
│   ├── delete_quotation.php
│   └── ... (other endpoints)
├── assets/
│   └── js/                  # JavaScript functionality
│       ├── invoices.js
│       └── quotation.js
├── config/
│   └── config.php          # Database configuration (uses .env)
├── database/
│   └── olivian_invoice.sql # Database schema
├── includes/               # Shared PHP templates
│   ├── navbar.php
│   └── footer.php
├── templates/              # Modal and form templates
│   ├── invoice_modal.php
│   └── quotation_modal.php
├── vendor/                 # Composer dependencies (not committed)
├── .env                    # Environment variables (not committed)
├── .env.example           # Environment template
├── .gitignore             # Git ignore rules
├── clients.php            # Client management page
├── invoices.php           # Invoice list page
├── quotations.php         # Quotation list page
├── settings.php           # Application settings
├── index.php              # Dashboard
└── README.md              # This file

API Endpoints

All endpoints return JSON responses.

Invoice Endpoints

• GET ajax/get_invoice.php?id=<id> - Fetch invoice with items
• POST ajax/save_invoice.php - Create/update invoice
• POST ajax/delete_invoice.php - Delete invoice
• POST ajax/mark_paid.php - Mark invoice as paid
• POST ajax/get_next_invoice_number.php - Generate next invoice number

Quotation Endpoints

• GET ajax/get_quotation.php?id=<id> - Fetch quotation with items
• POST ajax/save_quotation.php - Create/update quotation
• POST ajax/delete_quotation.php - Delete quotation
• POST ajax/get_next_quotation_number.php - Generate next quotation number

Security Considerations

• Database credentials are stored in .env and excluded from version control
• All database queries use prepared statements to prevent SQL injection
• .env file contains sensitive data and must never be committed
• Example .env.example is provided for configuration reference

Development

Running Locally

1. Ensure XAMPP or similar is running
2. Start MySQL service
3. Place project in htdocs directory
4. Access via http://localhost/Invoicing-system

File Modifications Log

Key files modified in this session:

• config/config.php - Updated to use environment variables
• .env - Created with database configuration
• .gitignore - Added to exclude sensitive files
• composer.json - Added vlucas/phpdotenv dependency
• Database schema - Added tax_rate column to invoices and quotations
• JavaScript files - Enhanced to handle tax calculations and storage

Contributing

1. Create a feature branch
2. Make changes
3. Commit with clear messages
4. Push to GitHub
5. Create pull request

Future Enhancements

• User authentication and authorization
• Email invoice delivery
• Payment gateway integration
• Recurring invoices
• Multi-currency support
• Advanced reporting
• Mobile app

Support

For issues and questions, please open an issue on GitHub: https://github.com/Varence-kiiru/Invoicing-system/issues

License

This project is licensed under the MIT License - see the LICENSE file for details.

Copyright (c) 2026 Varence Kiiru, Olivian Group

Author

Varence Kiiru - Initial development and maintenance

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Last Updated: March 2, 2026

For the latest version, visit: https://github.com/Varence-kiiru/Invoicing-system