Module: Lohnsteuer

Defined in:
lib/lohnsteuer.rb,
lib/lohnsteuer/version.rb

Constant Summary collapse

VERSION = 
"0.1.2"

Class Method Summary collapse

Class Method Details

.calculate(year, annual_salary, options = {}) ⇒ Object 



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# File 'lib/lohnsteuer.rb', line 53

def self.calculate(year, annual_salary, options = {})
  (1..12).map do |month|
    calculate_month(year, month, annual_salary / 12.0, options)
  end.inject(income_tax: 0, solidarity_tax: 0) do |res, item|
    res[:income_tax] = res[:income_tax] + item[:income_tax]
    res[:solidarity_tax] = res[:solidarity_tax] + item[:solidarity_tax]
    res
  end
end

.calculate_month(year, month, monthly_salary, options = {}) ⇒ Object 



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# File 'lib/lohnsteuer.rb', line 12

def self.calculate_month(year, month, monthly_salary, options = {})
  params = {
    # The tax class must be 1, 2, 3, 4, 5 or 6.
    STKL: options[:tax_class] || 1,

    # Monthly salary in Euro cent.
    RE4: monthly_salary * 100.0,

    # Configure the algorithm to calculate monthly taxes.
    LZZ: 2,

    # Health insurance state.
    # 0 = general health insurance.
    # 1 = private health insurance without employer supplement.
    # 2 = private health insurance with employer supplement.
    PKV: options[:health_insurance_state] || 0,

    # Additional contribution rate to the general health insurance.
    KVZ: options[:additional_contribution_rate] || 1.10,

    # Allow to deselect the calculation of the nursing care insurance.
    PVZ: options[:no_nursing_care_insurance] ? 0 : 1,

    # Number of children eligible for the children allowance.
    ZKF: options[:children] || 0
  }

  algorithm = tax_algorithms.find { |c| c.applies?(Date.new(year, month, 1)) }
  fail "No tax algorithm found for #{month}/#{year}" unless algorithm

  res = algorithm.calculate(params)

  total_income_tax = (res[:LSTLZZ] || 0) + (res[:STS] || 0) + (res[:STV] || 0)
  total_solidarity_tax = (res[:SOLZLZZ] || 0) + (res[:SOLZS] || 0) + (res[:SOLZV] || 0)

  {
    income_tax: total_income_tax / 100.0,
    solidarity_tax: total_solidarity_tax / 100.0
  }
end

.tax_algorithms ⇒ Object 



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# File 'lib/lohnsteuer.rb', line 8

def self.tax_algorithms
  [Lst2016, Lst1215]
end