# Phase 7C: Taxes - COMPLETE ✅

## Completion Date
December 16, 2024

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## Overview

Phase 7C implements comprehensive tax management including tax rates, tax categories, tax exemptions, and tax calculation services.

---

## ✅ Completed Deliverables

### 1. Tax Rate Service (`modules/taxes/services/taxRates.js`)
- ✅ `createTaxRate()` - Create tax rate
- ✅ `getTaxRate()` - Get tax rate by ID
- ✅ `updateTaxRate()` - Update tax rate
- ✅ `deleteTaxRate()` - Delete tax rate (validates no tax categories)
- ✅ `listTaxRates()` - List tax rates with filters and pagination
- ✅ `getTaxRateByCode()` - Get active tax rate by code

### 2. Tax Category Service (`modules/taxes/services/taxCategories.js`)
- ✅ `createTaxCategory()` - Create tax category linked to tax rate
- ✅ `getTaxCategory()` - Get tax category by ID
- ✅ `updateTaxCategory()` - Update tax category
- ✅ `deleteTaxCategory()` - Delete tax category (validates no products)
- ✅ `listTaxCategories()` - List tax categories with filters and pagination

### 3. Tax Exemption Service (`modules/taxes/services/taxExemptions.js`)
- ✅ `createTaxExemption()` - Create tax exemption (customer or product level)
- ✅ `getTaxExemption()` - Get tax exemption by ID
- ✅ `updateTaxExemption()` - Update tax exemption
- ✅ `deleteTaxExemption()` - Delete tax exemption
- ✅ `listTaxExemptions()` - List tax exemptions with filters and pagination

### 4. Tax Calculation Service (`modules/taxes/services/taxCalculation.js`)
- ✅ `calculateProductTax()` - Calculate tax for a product
- ✅ `checkTaxExemption()` - Check if product/customer has tax exemption
- ✅ `calculateSaleTaxes()` - Calculate taxes for multiple sale items
- ✅ `getProductTaxRate()` - Get applicable tax rate for a product

### 5. Tax Controllers (`modules/taxes/controllers/index.js`)
- ✅ Tax rate controllers (create, get, update, delete, list, getByCode)
- ✅ Tax category controllers (create, get, update, delete, list)
- ✅ Tax exemption controllers (create, get, update, delete, list)
- ✅ Tax calculation controllers (calculateProductTax, getProductTaxRate)
- ✅ All endpoints with proper error handling
- ✅ System logging integration

### 6. Tax Validations (`modules/taxes/validations/index.js`)
- ✅ Tax rate validations (create, update, get, delete, list, getByCode)
- ✅ Tax category validations (create, update, get, delete, list)
- ✅ Tax exemption validations (create, update, get, delete, list)
- ✅ Tax calculation validations (calculateProductTax, getProductTaxRate)
- ✅ Request body validation
- ✅ Query parameter validation
- ✅ Entity type validation (CUSTOMER/PRODUCT for exemptions)

### 7. Tax Routes (`modules/taxes/routes/index.js`)
- ✅ RESTful endpoints with Swagger documentation
- ✅ All routes integrated into main routes
- ✅ Authentication required
- ✅ Role-based access control (manager, system_admin for write operations)

---

## 📡 API Endpoints

### Tax Rates

#### Create Tax Rate
- **Endpoint:** `POST /api/taxes/tax-rates`
- **Auth:** Required (manager, system_admin)
- **Body:**
  ```json
  {
    "name": "VAT Standard",
    "code": "VAT_STANDARD",
    "rate": 16.0,
    "tax_type": "VAT",
    "description": "Standard VAT rate",
    "active": true
  }
  ```
- **Returns:** Created tax rate

#### Get Tax Rate by ID
- **Endpoint:** `GET /api/taxes/tax-rates/:id`
- **Auth:** Required
- **Returns:** Tax rate details

#### Update Tax Rate
- **Endpoint:** `PUT /api/taxes/tax-rates/:id`
- **Auth:** Required (manager, system_admin)
- **Body:** Same as create (all fields optional)
- **Returns:** Updated tax rate

#### Delete Tax Rate
- **Endpoint:** `DELETE /api/taxes/tax-rates/:id`
- **Auth:** Required (manager, system_admin)
- **Returns:** Success message
- **Note:** Cannot delete if has tax categories

#### List Tax Rates
- **Endpoint:** `GET /api/taxes/tax-rates?page=1&limit=10&tax_type=VAT&active=true`
- **Auth:** Required
- **Filters:**
  - `tax_type` - Filter by type (VAT, EXCISE, SALES_TAX, OTHER)
  - `active` - Filter by active status
- **Returns:** Paginated tax rates list

#### Get Tax Rate by Code
- **Endpoint:** `GET /api/taxes/tax-rates/code/:code`
- **Auth:** Required
- **Returns:** Active tax rate

### Tax Categories

#### Create Tax Category
- **Endpoint:** `POST /api/taxes/tax-categories`
- **Auth:** Required (manager, system_admin)
- **Body:**
  ```json
  {
    "tax_rate_id": 1,
    "name": "Standard Rate",
    "code": "STANDARD",
    "description": "Standard tax category"
  }
  ```
- **Returns:** Created tax category

#### Get Tax Category by ID
- **Endpoint:** `GET /api/taxes/tax-categories/:id`
- **Auth:** Required
- **Returns:** Tax category details

#### Update Tax Category
- **Endpoint:** `PUT /api/taxes/tax-categories/:id`
- **Auth:** Required (manager, system_admin)
- **Body:** Same as create (all fields optional)
- **Returns:** Updated tax category

#### Delete Tax Category
- **Endpoint:** `DELETE /api/taxes/tax-categories/:id`
- **Auth:** Required (manager, system_admin)
- **Returns:** Success message
- **Note:** Cannot delete if has products

#### List Tax Categories
- **Endpoint:** `GET /api/taxes/tax-categories?page=1&limit=10&tax_rate_id=1`
- **Auth:** Required
- **Filters:**
  - `tax_rate_id` - Filter by tax rate ID
- **Returns:** Paginated tax categories list

### Tax Exemptions

#### Create Tax Exemption
- **Endpoint:** `POST /api/taxes/tax-exemptions`
- **Auth:** Required (manager, system_admin)
- **Body:**
  ```json
  {
    "tax_category_id": 1,
    "entity_type": "CUSTOMER",
    "customer_id": 1,
    "certificate_number": "EX-12345",
    "effective_from": "2024-01-01T00:00:00Z",
    "effective_to": null,
    "active": true
  }
  ```
- **Returns:** Created tax exemption

#### Get Tax Exemption by ID
- **Endpoint:** `GET /api/taxes/tax-exemptions/:id`
- **Auth:** Required
- **Returns:** Tax exemption details

#### Update Tax Exemption
- **Endpoint:** `PUT /api/taxes/tax-exemptions/:id`
- **Auth:** Required (manager, system_admin)
- **Body:** Same as create (all fields optional)
- **Returns:** Updated tax exemption

#### Delete Tax Exemption
- **Endpoint:** `DELETE /api/taxes/tax-exemptions/:id`
- **Auth:** Required (manager, system_admin)
- **Returns:** Success message

#### List Tax Exemptions
- **Endpoint:** `GET /api/taxes/tax-exemptions?page=1&limit=10&entity_type=CUSTOMER&customer_id=1&active=true`
- **Auth:** Required
- **Filters:**
  - `entity_type` - Filter by entity type (CUSTOMER, PRODUCT)
  - `customer_id` - Filter by customer ID
  - `product_id` - Filter by product ID
  - `tax_category_id` - Filter by tax category ID
  - `active` - Filter by active status
- **Returns:** Paginated tax exemptions list (only shows currently effective exemptions)

### Tax Calculations

#### Calculate Product Tax
- **Endpoint:** `GET /api/taxes/calculate?product_id=1&quantity=2&unit_price=100.50&customer_id=1`
- **Auth:** Required
- **Query Parameters:**
  - `product_id` - Product ID (required)
  - `quantity` - Quantity (required)
  - `unit_price` - Unit price (required)
  - `customer_id` - Customer ID (optional, for exemption check)
- **Returns:** Tax calculation result

#### Get Product Tax Rate
- **Endpoint:** `GET /api/taxes/tax-rate?product_id=1&customer_id=1`
- **Auth:** Required
- **Query Parameters:**
  - `product_id` - Product ID (required)
  - `customer_id` - Customer ID (optional, for exemption check)
- **Returns:** Tax rate percentage

---

## 🔑 Key Features

### Tax Rates
- **Multiple tax types** (VAT, EXCISE, SALES_TAX, OTHER)
- **Rate percentage** (0-100%)
- **Active/inactive** status
- **Unique codes** for identification

### Tax Categories
- **Linked to tax rates** (one-to-many relationship)
- **Product assignment** (products can have tax categories)
- **Standard categories** (Standard Rate, Zero Rated, Exempt)

### Tax Exemptions
- **Customer-level exemptions** (entire customer exempt)
- **Product-level exemptions** (specific product exempt)
- **Effective date ranges** (effective_from, effective_to)
- **Certificate numbers** for tracking
- **Active/inactive** status

### Tax Calculation Logic
1. **Check for exemptions** (product-level or customer-level)
2. **Get tax rate** from product's tax category or default VAT rate
3. **Calculate tax amount** (line total * tax rate / 100)
4. **Return calculation** with line total, tax amount, and total with tax

---

## 📊 Database Schema

### TaxRate Table
- `id` - Primary key
- `name` - Tax rate name (required)
- `code` - Tax rate code (unique, required)
- `rate` - Tax rate percentage (0-100)
- `tax_type` - Tax type (VAT, EXCISE, SALES_TAX, OTHER)
- `active` - Active status
- `description` - Description (optional)

### TaxCategory Table
- `id` - Primary key
- `tax_rate_id` - Foreign key to tax_rates
- `name` - Category name (required)
- `code` - Category code (unique, required)
- `description` - Description (optional)

### TaxExemption Table
- `id` - Primary key
- `tax_category_id` - Foreign key to tax_categories
- `entity_type` - Entity type (CUSTOMER, PRODUCT)
- `customer_id` - Foreign key to customers (optional)
- `product_id` - Foreign key to products (optional)
- `certificate_number` - Certificate number (optional)
- `effective_from` - Effective start date
- `effective_to` - Effective end date (null for permanent)
- `active` - Active status

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## 📝 Business Rules

1. **Tax Rate Creation:**
   - Code must be unique
   - Rate must be between 0 and 100
   - Tax type must be valid enum value

2. **Tax Rate Deletion:**
   - Cannot delete if has tax categories

3. **Tax Category Creation:**
   - Must reference valid tax rate
   - Code must be unique

4. **Tax Category Deletion:**
   - Cannot delete if has assigned products

5. **Tax Exemption Creation:**
   - Must specify entity_type (CUSTOMER or PRODUCT)
   - If CUSTOMER, customer_id is required
   - If PRODUCT, product_id is required
   - Effective date ranges validated

6. **Tax Calculation:**
   - Checks exemptions first (product-level then customer-level)
   - Falls back to product's tax category rate
   - Falls back to product's default_vat_rate
   - Returns 0% if no tax rate found

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## ✅ Acceptance Criteria Met

- ✅ Tax rate CRUD operations working
- ✅ Tax category CRUD operations working
- ✅ Tax exemption CRUD operations working
- ✅ Tax calculation logic working
- ✅ Exemption checking working
- ✅ Integration with products working

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## 🚀 Next Steps

Phase 7 Complete: Enterprise Features (Categories, Pricing, Taxes) ✅

Phase 8: Advanced Sales Features
- Sales returns and refunds
- Sales reporting and analytics
- Customer loyalty programs

---

**Phase 7C Status: COMPLETE ✅**

