Add SNAP minimum benefit

CHANGELOG.md

@@ -29,3 +29,7 @@
 ## 0.7.0
 
 * Added Gains Tax (capital gains treatment) logic and parameters
+
+### 0.8.0
+
+* Added minimum benefit logic for SNAP

openfisca_us/parameters/usda/snap/minimum_benefit/maximum_household_size.yaml

@@ -0,0 +1,10 @@
+description: Maximum household size for SNAP minimum benefits
+
+values:
+  2021-01-01: 2
+
+metadata:
+  unit: persons
+  reference:
+  - title: '7 CFR § 273.10 - Determining household eligibility and benefit levels.'
+    href: https://www.law.cornell.edu/cfr/text/7/273.10#e_2_ii_C

openfisca_us/parameters/usda/snap/minimum_benefit/rate.yaml

@@ -0,0 +1,10 @@
+description: Minimum SNAP benefit as a fraction of maximum benefit
+
+values:
+  2021-01-01: 0.08 
+
+metadata:
+  unit: /1
+  reference:
+  - title: '7 CFR § 273.10 - Determining household eligibility and benefit levels.'
+    href: https://www.law.cornell.edu/cfr/text/7/273.10#e_2_ii_C

openfisca_us/parameters/usda/snap/minimum_benefit/relevant_max_benefit_household_size.yaml

@@ -0,0 +1,10 @@
+description: In calculating a SNAP minimum benefit, the household size to look up the relevant maximum benefit
+
+values:
+  2021-01-01: 1
+
+metadata:
+  unit: persons
+  reference:
+  - title: '7 CFR § 273.10 - Determining household eligibility and benefit levels.'
+    href: https://www.law.cornell.edu/cfr/text/7/273.10#e_2_ii_C

openfisca_us/tests/policy/baseline/usda/snap/snap_minimum_benefit.yaml

@@ -0,0 +1,42 @@
+- name: Family of 2
+  period: 2022
+  absolute_error_margin: 0.01
+  input:
+    people:
+      person_1:
+        age: 30
+      person_2:
+        age: 50
+    spm_units:
+      spm_unit:
+        members: [person_1, person_2]
+    households:
+      household:
+        state_group: CONTIGUOUS_US
+  output:
+    # Eligible as a family of 2.
+    # $204/mo is the maximum SNAP benefit for 1-person households in the
+    # contiguous US.
+    snap_minimum_benefit: 204 * 0.08 * 12
+
+
+- name: Family of 3
+  period: 2022
+  absolute_error_margin: 0.01
+  input:
+    people:
+      person_1:
+        age: 30
+      person_2:
+        age: 50
+      person_3:
+        age: 35
+    spm_units:
+      spm_unit:
+        members: [person_1, person_2, person_3]
+    households:
+      household:
+        state_group: CONTIGUOUS_US
+  output:
+    # Ineligible as a family of 3.
+    snap_minimum_benefit: 0

openfisca_us/tests/policy/baseline/usda/snap/standard_deduction.yaml

@@ -1,12 +1,3 @@
-# looks up from snap_standard_deduction.yaml based on state and Family size
-# TODO: rename all files basically with snap in front
-#       add snap in front of variable names 
-#       multiply gross income by 12
-#       rename income to gross income
-#       create snap gross income variable
-#       make sure items under metadata are indented properly for all files
-#       add household nesting for GU, VI, AK, HI, etc. non contiguous
-
 - name: Family of 4, income of 24k/year (Standard Test)
   period: 2021
   absolute_error_margin: 0.01

openfisca_us/variables/usda/snap/min_benefit.py

@@ -1,17 +1,30 @@
 from openfisca_us.model_api import *
 
 
-class snap_min_benefit(Variable):
+class snap_minimum_benefit(Variable):
     value_type = float
     entity = SPMUnit
-    label = "SNAP minimum benefit"
-    unit = "currency-USD"
-    documentation = "The SNAP entitlement that would be required to meet the minimum benefit requirement."
     definition_period = YEAR
+    label = "Minimum benefit for SNAP"
 
     def formula(spm_unit, period, parameters):
-        under_three_members = spm_unit.nb_persons() <= 2
-        single_person_max = parameters(period).usda.snap.amount.main[
-            spm_unit.household("state_group_str", period)
-        ]["1"]
-        return under_three_members * single_person_max * 0.08
+        # Parameters for the minimum benefit.
+        snap = parameters(period).usda.snap
+        min_benefit = snap.minimum_benefit
+        # Calculate the relevant maximum benefit, defined as the maximum
+        # benefit for a household of a certain size in their state.
+        state_group = spm_unit.household("state_group_str", period)
+        relevant_max_benefit = (
+            snap.amount.main[state_group][
+                str(min_benefit.relevant_max_benefit_household_size)
+            ]
+            * 12
+        )
+        # Minimum benefits only apply to households up to a certain size.
+        household_size = spm_unit.nb_persons()
+        min_share_of_max = where(
+            household_size <= min_benefit.maximum_household_size,
+            min_benefit.rate,
+            0,
+        )
+        return relevant_max_benefit * min_share_of_max

openfisca_us/variables/usda/snap/snap.py

@@ -16,6 +16,6 @@ def formula(spm_unit, period):
         eligible = spm_unit("is_snap_eligible", period)
         expected_contribution = spm_unit("snap_expected_contribution", period)
         return eligible * max_(
-            spm_unit("snap_min_benefit", period),
+            spm_unit("snap_minimum_benefit", period),
             spm_unit("snap_max_benefit", period) - expected_contribution,
         )

setup.py

@@ -4,7 +4,7 @@
 
 setup(
     name="OpenFisca-US",
-    version="0.7.0",
+    version="0.8.0",
     author="Nikhil Woodruff",
     author_email="nikhil@policyengine.org",
     classifiers=[
@@ -51,9 +51,7 @@
     },
     python_requires=">=3.7,<3.8",
     entry_points={
-        "console_scripts": [
-            "openfisca-us = openfisca_us.tools.cli:main",
-        ],
+        "console_scripts": ["openfisca-us = openfisca_us.tools.cli:main"],
     },
     packages=find_packages(),
 )