Payslip Generator

Running the application

./bin/generate-payslips <path-to-employee-data> <output-path-for-payslips>

Running the tests

bundle exec rake

Building tax bracket yaml files

Example:

- multiplier: 0.0
  min: 0
  max: 18200
- multiplier: 0.19
  min: 18201
  max: 37000
- multiplier: 0.325
  min: 37001
  max: 80000
- multiplier: 0.37
  min: 80001
  max: 180000
- multiplier: 0.45
  min: 180001
  max: -1

Max of -1 is the equivilant of infinite.

Design decisions

Tax Bracket

The Tax Bracket object takes a range and a multiplier, the idea behind this is that for a given tax system you will need to create multiple tax brackets and then apply them to a TaxCalculator, this provides the ability to support multiple tax systems.

Tax Calculator

This is essentially a pretty simple object that takes a salary and an array of tax brackets and sums all the tax bracket calculations and rounds accordingly.

Payslip Factory

Initially I was going to have all the calculations as separate classes but I felt the calculations were too simple to have in a single class as often they're just basic math operations.

The class only calculates monthly payslips, it doesn't support partial months, this is to keep the first implementation simple. If I was to implement this I would inject an object which calculates a multiplier based on a date range.

Payslip Writers && Employee Readers

At the moment the only implementation supported is writing to CSV but I've implemented it so that you could inject any writer or reader in that adheres to the writer or reader interface.

Assumptions made

Majority of tax calculations are performed using some form of bracket system. This assumption is based on information collected from the UK, Germany, Australia and New Zealand tax system.
Pay periods aren't taken into consideration when it comes to calculating the monthly pay, so this solution doesn't cater for partial months only for full months.
CSV file will not have headers in it.
CSV file will always be provided in the correct format

Future improvements

Add more tax bracket configuration files and add country code as an arguement for the generate-payslips script
Make the CSV Reader a little smarter in regards to format checking.

treacher/payslip_generator