Create standard deduction, update federal tax data migration. (#44)

* Update federal tax bracket data migration.

* Add standard deduction to db.

* Monetize standard deduction.

* Add specs.

* Update specs.

app/models/standard_deduction.rb

@@ -0,0 +1,16 @@
+# == Schema Information
+#
+# Table name: standard_deductions
+#
+#  id              :bigint           not null, primary key
+#  amount_cents    :integer          default(0), not null
+#  amount_currency :string           default("USD"), not null
+#  created_at      :datetime         not null
+#  updated_at      :datetime         not null
+#
+class StandardDeduction < ApplicationRecord
+  monetize :amount_cents
+
+  validates :amount_cents, presence: true
+  validates :amount_currency, presence: true
+end

app/services/federal_tax_calculator.rb

@@ -22,6 +22,6 @@ def calculate
 
   def taxable_income
     # 2024 standard deduction = 13,850
-    @taxable_income ||= income - Money.new(13_850_00)
+    @taxable_income ||= income - StandardDeduction.first.amount
   end
 end

db/data/20240711124610_create_tax_tables.rb

@@ -2,13 +2,14 @@
 
 class CreateTaxTables < ActiveRecord::Migration[7.0]
   def up
-    FederalTaxBracket.create(tier: "Tier 1", bottom_range: 0, top_range: 23_200, rate: 0.1, cumulative: 0)
-    FederalTaxBracket.create(tier: "Tier 2", bottom_range: 23_001, top_range: 94_300, rate: 0.12, cumulative: 2_320)
-    FederalTaxBracket.create(tier: "Tier 3", bottom_range: 94_301, top_range: 201_050, rate: 0.22, cumulative: 10_852)
-    FederalTaxBracket.create(tier: "Tier 4", bottom_range: 201_051, top_range: 383_900, rate: 0.24, cumulative: 34_337)
-    FederalTaxBracket.create(tier: "Tier 5", bottom_range: 383_901, top_range: 487_450, rate: 0.32, cumulative: 78_221)
-    FederalTaxBracket.create(tier: "Tier 6", bottom_range: 487_451, top_range: 731_200, rate: 0.35, cumulative: 111_357)
-    FederalTaxBracket.create(tier: "Tier 7", bottom_range: 731_201, top_range: 10_000_000, rate: 0.35, cumulative: 196_669)
+    # Federal tax brackets for single filers in 2024
+    FederalTaxBracket.create(tier: "Tier 1", bottom_range: 0, top_range: 11_600, rate: 0.1, cumulative: 0)
+    FederalTaxBracket.create(tier: "Tier 2", bottom_range: 11_601, top_range: 47_150, rate: 0.12, cumulative: 1_160)
+    FederalTaxBracket.create(tier: "Tier 3", bottom_range: 47_151, top_range: 100_525, rate: 0.22, cumulative: 5_426)
+    FederalTaxBracket.create(tier: "Tier 4", bottom_range: 100_526, top_range: 191_950, rate: 0.24, cumulative: 17_168.5)
+    FederalTaxBracket.create(tier: "Tier 5", bottom_range: 191_951, top_range: 243_725, rate: 0.32, cumulative: 39_110.5)
+    FederalTaxBracket.create(tier: "Tier 6", bottom_range: 243_726, top_range: 609_350, rate: 0.35, cumulative: 55_678.5)
+    FederalTaxBracket.create(tier: "Tier 7", bottom_range: 609_351, top_range: 10_000_000, rate: 0.35, cumulative: 183_647.25)
   end
 
   def down

db/data/20240715131425_create_standard_deduction.rb

@@ -0,0 +1,12 @@
+# frozen_string_literal: true
+
+class CreateStandardDeduction < ActiveRecord::Migration[7.0]
+  def up
+    #  2024 Standard Deduction is $13,850
+    StandardDeduction.create(amount: 13_850)
+  end
+
+  def down
+    raise ActiveRecord::IrreversibleMigration
+  end
+end

db/data_schema.rb

@@ -1 +1 @@
-DataMigrate::Data.define(version: 20240711132613)
+DataMigrate::Data.define(version: 20240715131425)

db/migrate/20240715131211_create_standard_deductions.rb

@@ -0,0 +1,9 @@
+class CreateStandardDeductions < ActiveRecord::Migration[7.0]
+  def change
+    create_table :standard_deductions do |t|
+      t.monetize :amount
+
+      t.timestamps
+    end
+  end
+end

spec/factories/standard_deductions.rb

@@ -0,0 +1,17 @@
+# == Schema Information
+#
+# Table name: standard_deductions
+#
+#  id              :bigint           not null, primary key
+#  amount_cents    :integer          default(0), not null
+#  amount_currency :string           default("USD"), not null
+#  created_at      :datetime         not null
+#  updated_at      :datetime         not null
+#
+FactoryBot.define do
+  factory :standard_deduction do
+    # standard deduction amount is $13,850
+    amount_cents { 1_385_000 }
+    amount_currency { "USD" }
+  end
+end

spec/features/dashboard/dashboard_spec.rb

@@ -9,6 +9,7 @@
   let!(:fixed_expenses) { create_list(:fixed_expense, 2) }
   let!(:saving_rate) { create(:savings_rate) }
   let!(:investing_rate) { create(:savings_rate, name: "investing", rate: 0.02) }
+  let!(:standard_deduction) { create(:standard_deduction) }
 
   describe "GET /index" do
     it "routes to root path" do

spec/models/standard_deduction_spec.rb

@@ -0,0 +1,16 @@
+# == Schema Information
+#
+# Table name: standard_deductions
+#
+#  id              :bigint           not null, primary key
+#  amount_cents    :integer          default(0), not null
+#  amount_currency :string           default("USD"), not null
+#  created_at      :datetime         not null
+#  updated_at      :datetime         not null
+#
+require "rails_helper"
+
+RSpec.describe StandardDeduction, type: :model do
+  it { is_expected.to validate_presence_of(:amount_cents) }
+  it { is_expected.to validate_presence_of(:amount_currency) }
+end

spec/services/federal_tax_calculator_spec.rb

@@ -11,6 +11,7 @@
 
   let!(:salary_income) { create(:income) }
   let!(:tax_brackets) { create(:federal_tax_bracket, :with_all_tiers) }
+  let!(:standard_deduction) { create(:standard_deduction) }
 
   it { expect(service).to be_a Money }