paye 1.0.5

A Dart package for calculating PAYE (Pay As You Earn) tax and pension contributions.

PayE Dart Implementation

A complete Dart implementation of the PayE payroll and pension management system, featuring progressive subtraction tax calculation and comprehensive payroll reporting.

Features

• Multi-country support with configurable tax brackets
• Progressive subtraction tax calculation where threshold amounts are progressively subtracted from basic salary
• Flexible salary calculation supporting both basic salary and piece-rate work
• Pension contribution calculations with configurable tiered allocation
• Detailed payroll reporting with step-by-step tax calculation breakdown
• Configurable salary splitting between basic salary and allowances
• No automatic sorting - tax brackets are processed in the exact order they were entered

Progressive Subtraction Tax Calculation

The system implements a progressive subtraction tax calculation where:

1. Each threshold amount gets taxed at its respective rate
2. Threshold amounts are progressively subtracted from the basic salary
3. Tax calculation: Each threshold amount × its tax rate = tax for that amount
4. PAYE tax: Sum of all calculated tax amounts
5. Net salary: Original salary minus total tax

Example Tax Bracket Setup:

Threshold 490: 0% tax = 0.00 tax
Threshold 110: 5% tax = 5.50 tax
Threshold 130: 10% tax = 13.00 tax
Threshold 3166: 17.5% tax = 554.05 tax
Threshold 16000: 25% tax = 4,000.00 tax
Threshold 30520: 30% tax = 9,156.00 tax

Progressive Subtraction Example:

Starting salary: 50,416.67

• Subtract 490 → Remaining: 49,926.67, Tax: 0.00
• Subtract 110 → Remaining: 49,816.67, Tax: 5.50
• Subtract 130 → Remaining: 49,686.67, Tax: 13.00
• Subtract 3166 → Remaining: 46,520.67, Tax: 554.05
• Subtract 16000 → Remaining: 30,520.67, Tax: 4,000.00
• Subtract 30520 → Remaining: 0.00, Tax: 9,156.00

Total PAYE Tax: 13,728.55

Project Structure

PayE_Dart/
├── lib/
│   ├── main.dart          # Main application entry point
│   ├── types.dart          # Core data structures
│   ├── payroll.dart        # Payroll and tax calculations
│   └── pension.dart        # Pension calculations
├── pubspec.yaml            # Dart project configuration
└── README.md               # This file

Installation

1. Install Dart SDK (version 3.0.0 or higher)
2. Clone or download the PayE_Dart folder
3. Navigate to the project directory:

   cd PayE_Dart
   

4. Get dependencies:

   dart pub get
   

Usage

Run the Application

dart run lib/main.dart

Interactive Setup Process

1. Pension Tier Setup

   • Enter custom pension tiers (total must equal 100%)
   • Or use default tiers if total doesn't reach 100%

2. Country Setup

   • Enter country code (3 letters)
   • Enter country name and minimum wage
   • Set up tax brackets (threshold amounts and rates)
   • Minimum wage automatically gets 0% tax rate

3. Salary Configuration

   • Enable/disable salary splitting
   • Configure basic salary and allowance ratios

4. Employee Setup

   • Enter employee details
   • Set basic salary and/or piece-rate work
   • Assign country code

5. Payroll Processing

   • Automatic tax calculation using progressive subtraction
   • Pension calculations with tier allocations
   • Comprehensive payroll reports

Key Classes

Employee

• Basic salary, piece-rate work, country information
• Automatic calculation of total earnings

TaxBracket

• Threshold amount and tax rate
• No automatic sorting - preserves input order

PensionCalculator

• Employee and employer contributions
• Tier-based allocation system
• Configurable contribution rates

PayrollCalculator

• Progressive subtraction tax calculation
• Salary and piece-rate calculations
• Comprehensive reporting functions

Tax Calculation Algorithm

// Progressive subtraction: each threshold amount is subtracted from basic salary
double remainingSalary = originalSalary;
for (final bracket in enhancedBrackets) {
  if (remainingSalary >= bracket.threshold) {
    // Tax at the threshold rate for the full threshold amount
    taxAmount = bracket.threshold * (bracket.rate / 100);
    remainingSalary -= bracket.threshold;
  } else if (remainingSalary > 0) {
    // Apply the same rate to the remaining salary
    taxAmount = remainingSalary * (bracket.rate / 100);
    remainingSalary = 0;
  }
  totalTax += taxAmount;
}

Example Output

Progressive Subtraction Tax Calculation Steps:
Step | Remaining Salary | Subtract Amount | Tax Rate | Tax Amount
-----|------------------|----------------|----------|-----------
   1 |         50416.67 |         490.00 |     0.0% |       0.00
   2 |         49926.67 |         110.00 |     5.0% |       5.50
   3 |         49816.67 |         130.00 |    10.0% |      13.00
   4 |         49686.67 |        3166.00 |    17.5% |     554.05
   5 |         46520.67 |       16000.00 |    25.0% |    4000.00
   6 |         30520.67 |       30520.00 |    30.0% |    9156.00

Total Tax: 13728.55

Dependencies

• Dart SDK: >=3.0.0
• args: ^2.4.0 (for command-line argument parsing)

Development

Run Tests

dart test

Format Code

dart format .

Analyze Code

dart analyze

Differences from Go Implementation

1. Immutable vs Mutable: Dart classes use mutable fields for runtime modifications
2. Records: Uses Dart 3.0+ records for returning multiple values
3. Null Safety: Full null safety implementation
4. Collections: Uses Dart's built-in collection methods (fold, map, etc.)
5. String Interpolation: Modern Dart string interpolation syntax

License

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