Salary Slip Kataλ︎
Pracitcalli Clojure CLI Config provides the :project/create alias to create projects using deps-new project.
Problem descriptionλ︎
A typical salary slip contains employee details like employee id, employee name and their monthly salary details like their gross salary, national insurance contributions, tax-free allowance, taxable income and tax payable.
Salary slips are generated each month for every employee.
Acceptance criteriaλ︎
- Salary slip generator should receive an employee with its Employee Id, Employee Name and Annual Gross Salary
- Salary slip should contain the Employee ID, Employee Name, Gross Salary, National Insurance contributions, Tax-free allowance, Taxable income and Tax payable for the month
- The entry point should be the following public function API
Iterationsλ︎
Each iteration adds more rules to the calculation. Some iterations also introduce new fields to the salary slip.
In a given iteration, all the salary slips contain the same number fields for each employee (if a tax or contribution does not apply for a given employee, just put £0.00).
This means that for each iteration you will need to add fields to the SalarySlip class. In the first iteration, SalarySlip only contains the Employee ID, Employee Name and Monthly Gross Salary.
Iteration 1: for an annual salary of £5,000.00λ︎
This is the most basic case.
- Given I have an employee John J Doe with an annual gross salary of £5,000.00
- When I generate a monthly salary slip for the employee
- Then the monthly salary slip should contain the below
Employee ID: 12345 Employee Name: John J Doe Gross Salary: £416.67
Calculation rules:
- Monthly Gross Salary: The monthly gross salary is the employee's annual gross salary divided by 12
Iteration 2: for an annual gross salary of £9,060.00λ︎
Here we introduce the National Insurance contribution
The monthly salary slip should contain the below:
Employee ID: 12345
Employee Name: John J Doe
Gross Salary: £755.00
National Insurance contributions: £10.00
Calculation rules:
- National Insurance contributions: Any amount of money earned above a gross annual salary of £8,060.00 is subject to a National Insurance contribution of 12%
Iteration 3: for an annual gross salary of £12,000.00λ︎
This employee also needs to pay taxes
The monthly salary slip should contain the below:
Employee ID: 12345
Employee Name: John J Doe
Gross Salary: £1,000.00
National Insurance contributions: £39.40
Tax-free allowance: £916.67
Taxable income: £83.33
Tax Payable: £16.67
Calculation rules:
- Taxable income: Any amount of money earned above a gross annual salary of £11,000.00 is taxed at 20%
Iteration 4: for an annual gross salary of £45,000.00λ︎
This employee pays a higher band of National Insurance and Income Tax.
The monthly salary slip should contain the below:
Employee ID: 12345
Employee Name: John J Doe
Gross Salary: £3,750.00
National Insurance contributions: £352.73
Tax-free allowance: £916.67
Taxable income: £2,833.33
Tax Payable: £600.00
Calculation rules:
- Taxable income (higher rate): Any amount of money earned above a gross annual salary of £43,000.00 is taxed at 40%
- National Insurance (higher contributions): Any amount of money earned above a gross annual salary of £43,000.00 is only subject to a 2% NI contribution
Iteration 5: for annual gross salaries of £101,000.00; £111,000.00; £122,000.00 and £150,000.00λ︎
For high earners, the tax-free allowance decreases.
The monthly salary slips should contain the below (respectively):
Employee ID: 12345
Employee Name: John J Doe
Gross Salary: £8,416.67
National Insurance contributions: £446.07
Tax-free allowance: £875.00
Taxable income: £7,541.67
Tax Payable: £2,483.33
Employee ID: 12345
Employee Name: John J Doe
Gross Salary: £9,250.00
National Insurance contributions: £462.73
Tax-free allowance: £458.33
Taxable income: £8,791.67
Tax Payable: £2,983.33
Employee ID: 12345
Employee Name: John J Doe
Gross Salary: £10,166.67
National Insurance contributions: £481.07
Tax-free allowance: £0.00
Taxable income: £10,166.67
Tax Payable: £3,533.33
Employee ID: 12345
Employee Name: John J Doe
Gross Salary: £12,500.00
National Insurance contributions: £527.73
Tax-free allowance: £0.00
Taxable income: £12,500.00
Tax Payable: £4,466.67
Calculation rules:
- Tax-free allowance: When the Annual Gross Salary exceeds £100,000.00, the tax-free allowance starts decreasing. It decreases by £1 for every £2 earned over £100,000.00. And this excess is taxed at the Higher rate tax.
Iteration 6: for an annual gross salary of £160,000.00λ︎
The employee goes into the additional rate band.
The monthly salary slip should contain the below:
Employee ID: 12345
Employee Name: John J Doe
Gross Salary: £13,333.33
National Insurance contributions: £544.40
Tax-free allowance: £0.00
Taxable income: £13,333.33
Tax Payable: £4,841.67
Calculation rules:
- Income tax (additional rate band) : Any amount of money earned above a gross annual salary of £150,000.00 is taxed at 45%
Practicalli Salary Slip Kata
Salary slip kata - Devoxx 2019
(ns salary-slip-kata.core
"Developer Anarchy by Fred George
- made devs write the same solution in different languages
-- helps devs master the business domain
-- helps devs master technology domain")
(defn- national-insurance-contribution
"Calculate the national insurance contribution due for a given annual salary.
---------------------+-------------------------+--------
Band | NI deductible income | NI Rate
---------------------+-------------------------+--------
No contributions | Up to £8,060.00 | 0%
Basic contributions | £8,060.00 to £43,000.00 | 12%
Higher contributions | over £43,000.00 | 2%
---------------------+-------------------------+-------- "
[annual-gross-salary]
;; add a cond statement to return the calculate the value with respect to the band.
(* annual-gross-salary 0.12))
;; taxable income
;; ---------------------+---------------------------+---------
;; Band | Taxable income | Tax rate
;; ---------------------+---------------------------+---------
;; Personal Allowance* | Up to £11,000.00 | 0%
;; Basic rate | £11,000.00 to £43,000.00 | 20%
;; Higher rate | £43,000.00 to £150,000.00 | 40%
;; Additional rate | over £150,000.00 | 45%
;; ---------------------+---------------------------+---------
(defn salary-slip
"Creates a salary slip for a person
Specifically for employee of 24K annual salary"
[{:keys [employee-id
employee-name
annual-gross-salary]}]
(let [tax-free-allowance 11000
taxable-income (- annual-gross-salary
tax-free-allowance)]
{:employee-id employee-id
:employee-name employee-name
:gross-salary (/ annual-gross-salary 12)
:national-insurance (national-insurance-contribution annual-gross-salary)
:tax-free-allowance tax-free-allowance
:taxable-income taxable-income
:tax-payable (* taxable-income 0.20)}))