Add liquid asset variables for SSI modeling

changelog_entry.yaml

@@ -0,0 +1,8 @@
+- bump: minor
+  changes:
+    added:
+      - Add liquid asset input variables (bank_account_assets, stock_assets, bond_assets), ssi_countable_resources, and spm_unit_cash_assets aggregation
+      - Add takes_up_ssi_if_eligible variable for SSI takeup modeling
+    changed:
+      - SSI resource test now uses actual imputed assets instead of random pass rate
+      - SSI benefit now applies takeup in microsimulation

policyengine_us/parameters/gov/ssa/ssi/eligibility/resources/README.md

@@ -1,10 +1,16 @@
 # Resources
 
-[SSA reported $5.293 billion in SSI expenditures in February 2023](https://www.ssa.gov/policy/docs/quickfacts/stat_snapshot/#table3).
-Adjust `pass_rate.yaml` to match this for SSI in 2023 ($5.293 billion * 12 = $63.5 billion).
+SSI countable resources are now calculated from imputed liquid assets
+(bank accounts, stocks, bonds) rather than using a random pass rate.
+
+The assets are imputed from SIPP in policyengine-us-data and flow through
+to the SSI resource test via `ssi_countable_resources`.
 
-Check with this code:
+Check SSI expenditures with:
 ```python
 from policyengine_us import Microsimulation
 Microsimulation().calc("ssi", map_to="person", period=2023).sum() / 1e9
 ```
+
+[SSA reported $5.293 billion in SSI expenditures in February 2023](https://www.ssa.gov/policy/docs/quickfacts/stat_snapshot/#table3).
+Annual target: $5.293 billion * 12 = $63.5 billion.

policyengine_us/parameters/gov/ssa/ssi/eligibility/resources/countable.yaml

@@ -0,0 +1,20 @@
+description: >-
+  The US counts these asset types as countable resources for SSI eligibility.
+  Excludes home, one vehicle, household goods, burial plots, and retirement accounts.
+values:
+  1975-01-01:
+    # Liquid assets counted as resources
+    - bank_account_assets  # Checking, savings, money market
+    - stock_assets  # Stocks and mutual funds
+    - bond_assets  # Bonds and government securities
+metadata:
+  label: SSI countable resource sources
+  reference:
+    - title: SSA POMS SI 01140.200 - Checking and Savings Accounts
+      href: https://secure.ssa.gov/poms.nsf/lnx/0501140200
+    - title: SSA POMS SI 01140.220 - Stocks
+      href: https://secure.ssa.gov/poms.nsf/lnx/0501140220
+    - title: SSA POMS SI 01140.240 - U.S. Savings Bonds
+      href: https://secure.ssa.gov/poms.nsf/lnx/0501140240
+    - title: SSA POMS SI 01140.250 - Municipal, Corporate and Government Bonds
+      href: https://secure.ssa.gov/poms.nsf/lnx/0501140250

policyengine_us/variables/gov/ssa/ssi/eligibility/resources/meets_ssi_resource_test.py

@@ -5,8 +5,8 @@ class meets_ssi_resource_test(Variable):
     value_type = bool
     entity = Person
     label = "Meets SSI resource test"
-    unit = USD
     definition_period = YEAR
+    reference = "https://secure.ssa.gov/poms.nsf/lnx/0501110000"
 
     def formula(person, period, parameters):
         p = parameters(period).gov.ssa.ssi

policyengine_us/variables/gov/ssa/ssi/eligibility/resources/ssi_countable_resources.py

@@ -5,5 +5,15 @@ class ssi_countable_resources(Variable):
     value_type = float
     entity = Person
     label = "SSI countable resources"
+    documentation = (
+        "Countable resources for SSI eligibility. Includes liquid assets "
+        "(bank accounts, stocks, bonds) but excludes home, one vehicle, "
+        "household goods, and retirement accounts per SSI rules."
+    )
     unit = USD
     definition_period = YEAR
+    reference = (
+        "https://secure.ssa.gov/poms.nsf/lnx/0501140000",  # POMS SI 01140.000 - Types of Countable Resources
+    )
+
+    adds = "gov.ssa.ssi.eligibility.resources.countable"

policyengine_us/variables/gov/ssa/ssi/ssi.py

@@ -30,8 +30,11 @@ def formula(person, period, parameters):
         individual_max = p.individual * MONTHS_IN_YEAR
         capped_benefit = min_(benefit, individual_max)
 
-        return where(
+        final_benefit = where(
             deeming_applies,
             capped_benefit,
             benefit,
         )
+
+        takes_up = person("takes_up_ssi_if_eligible", period)
+        return final_benefit * takes_up

policyengine_us/variables/gov/ssa/ssi/takes_up_ssi_if_eligible.py

@@ -0,0 +1,9 @@
+from policyengine_us.model_api import *
+
+
+class takes_up_ssi_if_eligible(Variable):
+    value_type = bool
+    entity = Person
+    label = "Takes up SSI if eligible"
+    definition_period = YEAR
+    default_value = True

policyengine_us/variables/household/assets/bank_account_assets.py

@@ -0,0 +1,15 @@
+from policyengine_us.model_api import *
+
+
+class bank_account_assets(Variable):
+    value_type = float
+    entity = Person
+    label = "Bank account assets"
+    documentation = (
+        "Value of checking, savings, and money market accounts. "
+        "Imputed from SIPP TVAL_BANK."
+    )
+    unit = USD
+    definition_period = YEAR
+    uprating = "gov.bls.cpi.cpi_u"
+    reference = "https://secure.ssa.gov/poms.nsf/lnx/0501140200"

policyengine_us/variables/household/assets/bond_assets.py

@@ -0,0 +1,18 @@
+from policyengine_us.model_api import *
+
+
+class bond_assets(Variable):
+    value_type = float
+    entity = Person
+    label = "Bond assets"
+    documentation = (
+        "Value of bonds and government securities. "
+        "Imputed from SIPP TVAL_BOND."
+    )
+    unit = USD
+    definition_period = YEAR
+    uprating = "gov.bls.cpi.cpi_u"
+    reference = (
+        "https://secure.ssa.gov/poms.nsf/lnx/0501140240",
+        "https://secure.ssa.gov/poms.nsf/lnx/0501140250",
+    )

policyengine_us/variables/household/assets/spm_unit_cash_assets.py

@@ -7,3 +7,5 @@ class spm_unit_cash_assets(Variable):
     label = "SPM unit cash assets"
     definition_period = YEAR
     unit = USD
+
+    adds = ["bank_account_assets", "stock_assets", "bond_assets"]

policyengine_us/variables/household/assets/stock_assets.py

@@ -0,0 +1,14 @@
+from policyengine_us.model_api import *
+
+
+class stock_assets(Variable):
+    value_type = float
+    entity = Person
+    label = "Stock assets"
+    documentation = (
+        "Value of stocks and mutual funds. " "Imputed from SIPP TVAL_STMF."
+    )
+    unit = USD
+    definition_period = YEAR
+    uprating = "gov.bls.cpi.cpi_u"
+    reference = "https://secure.ssa.gov/poms.nsf/lnx/0501140220"