South Carolina Net Capital Gain Deduction

changelog_entry.yaml

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+- bump: minor
+  changes:
+    added:
+    - South Carolina net capital gain deduction.

policyengine_us/parameters/gov/states/sc/tax/income/deductions/net_capital_gains_deduction/rate.yaml

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+description: Net capital gains included in taxable income are reduced by this rate for South Carolina Income tax.
+values:
+  2021-01-01: 0.44 
+metadata:
+  unit: /1
+  label: South Carolina Net Capital Gain Rate
+  reference:
+  - title: SC1040 tax form (2021)
+    href: https://dor.sc.gov/forms-site/Forms/SC1040_2021.pdf#page=2
+  - title: Instructions for Form SC-1040 (line 3i)
+    href: https://dor.sc.gov/forms-site/Forms/IITPacket_2021.pdf#page=15
+  - title: South Carolina Code of Laws Section 12-6-1150 (A)
+    href: https://www.scstatehouse.gov/code/t12c006.php
+  - title: SC1040 tax form (2022)
+    href: https://dor.sc.gov/forms-site/Forms/SC1040_2022.pdf#page=2

policyengine_us/tests/policy/baseline/gov/states/sc/tax/income/deductions/net_captial_gains_deductions/sc_net_capital_gains_deductions.yaml

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+- name: Long term capital gains $10000, long term capital loss $3000, short term capital loss $5000
+  period: 2021
+  input:
+    state_code: SC
+    long_term_capital_gains: 7_000
+    #long_term_capital_losses: 3_000
+    #short_term_capital_losses: 5_000 
+    short_term_capital_gains: -5_000
+  output: 
+    sc_net_capital_gains_deduction: 880
+    # (10000-3000-5000) *0.44 = 880
+
+- name: Long term capital gains $3000, long term capital loss $10000, short term capital loss $5000
+  period: 2021
+  input:
+    state_code: SC
+    long_term_capital_gains: -7_000
+    #long_term_capital_losses: 10_000
+    #short_term_capital_losses: 5_000 
+    short_term_capital_gains: -5_000
+  output: 
+    sc_net_capital_gains_deduction: 0
+
+- name: Long term capital gains $6000, long term capital loss $3000, short term capital loss $5000
+  period: 2021
+  input:
+    state_code: SC
+    long_term_capital_gains: 3_000
+    #long_term_capital_losses: 3_000
+    #short_term_capital_losses: 5_000 
+    short_term_capital_gains: -5_000
+  output: 
+    sc_net_capital_gains_deduction: 0

policyengine_us/variables/gov/states/sc/tax/income/deductions/net_capital_gains_deduction/sc_net_capital_gain_deduction.py

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+from policyengine_us.model_api import *
+
+
+class sc_net_capital_gains_deduction(Variable):
+    value_type = float
+    entity = TaxUnit
+    label = "South Carolina net capital gains deduction"
+    unit = USD
+    definition_period = YEAR
+    defined_for = StateCode.SC
+    reference = (
+        "https://dor.sc.gov/forms-site/Forms/IITPacket_2021.pdf#page=15"
+    )
+
+    def formula(tax_unit, period, parameters):
+        p = parameters(
+            period
+        ).gov.states.sc.tax.income.deductions.net_capital_gains_deduction
+        sc_net_long_term_capital_gains = max_(
+            0, add(tax_unit, period, ["long_term_capital_gains"])
+        )
+        # ltcl = add(tax_unit, period, ["long_term_capital_losses"])
+        # stcl = add(tax_unit, period, ["short_term_capital_losses"])
+        sc_net_short_term_capital_gains = add(
+            tax_unit, period, ["short_term_capital_gains"]
+        )
+
+        # SC Net Captial Gain = (ltcg-ltcl)-stcl
+        # sc_net_long_term_capital_gains = max_(ltcg - ltcl, 0)
+        # sc_net_capital_gains = max_(sc_net_long_term_capital_gains - stcl, 0)
+
+        sc_net_capital_gains = max_(
+            0, sc_net_long_term_capital_gains + sc_net_short_term_capital_gains
+        )
+        return sc_net_capital_gains * p.rate