PolicyEngine · juaristi22 · Jul 15, 2025 · Jul 15, 2025 · Jul 15, 2025 · Jul 15, 2025
diff --git a/changelog_entry.yaml b/changelog_entry.yaml
@@ -0,0 +1,5 @@
+- bump: minor
+  changes:
+    added:
+    - Renaming variables to lowercase. 
+    - Extending the use of "p" for "parameter" in variable formulas.
diff --git a/...ngine_uk/parameters/gov/dwp/ESA/README.md → ...ngine_uk/parameters/gov/dwp/esa/README.md b/...ngine_uk/parameters/gov/dwp/ESA/README.md → ...ngine_uk/parameters/gov/dwp/esa/README.md
diff --git a/...k/parameters/gov/dwp/ESA/income/README.md → ...k/parameters/gov/dwp/esa/income/README.md b/...k/parameters/gov/dwp/ESA/income/README.md → ...k/parameters/gov/dwp/esa/income/README.md
diff --git a/...ters/gov/dwp/ESA/income/amount_18_24.yaml → ...ters/gov/dwp/esa/income/amount_18_24.yaml b/...ters/gov/dwp/ESA/income/amount_18_24.yaml → ...ters/gov/dwp/esa/income/amount_18_24.yaml
diff --git a/...rs/gov/dwp/ESA/income/amount_over_25.yaml → ...rs/gov/dwp/esa/income/amount_over_25.yaml b/...rs/gov/dwp/ESA/income/amount_over_25.yaml → ...rs/gov/dwp/esa/income/amount_over_25.yaml
diff --git a/...parameters/gov/dwp/ESA/income/couple.yaml → ...parameters/gov/dwp/esa/income/couple.yaml b/...parameters/gov/dwp/ESA/income/couple.yaml → ...parameters/gov/dwp/esa/income/couple.yaml
diff --git a/...rs/gov/dwp/ESA/income/earn_disregard.yaml → ...rs/gov/dwp/esa/income/earn_disregard.yaml b/...rs/gov/dwp/ESA/income/earn_disregard.yaml → ...rs/gov/dwp/esa/income/earn_disregard.yaml
diff --git a/...p/ESA/income/income_disregard_couple.yaml → ...p/esa/income/income_disregard_couple.yaml b/...p/ESA/income/income_disregard_couple.yaml → ...p/esa/income/income_disregard_couple.yaml
diff --git a/.../income/income_disregard_lone_parent.yaml → .../income/income_disregard_lone_parent.yaml b/.../income/income_disregard_lone_parent.yaml → .../income/income_disregard_lone_parent.yaml
diff --git a/...p/ESA/income/income_disregard_single.yaml → ...p/esa/income/income_disregard_single.yaml b/...p/ESA/income/income_disregard_single.yaml → ...p/esa/income/income_disregard_single.yaml
diff --git a/...gov/dwp/ESA/income/pension_disregard.yaml → ...gov/dwp/esa/income/pension_disregard.yaml b/...gov/dwp/ESA/income/pension_disregard.yaml → ...gov/dwp/esa/income/pension_disregard.yaml
diff --git a/...gine_uk/parameters/gov/dwp/IIDB/README.md → ...gine_uk/parameters/gov/dwp/iidb/README.md b/...gine_uk/parameters/gov/dwp/IIDB/README.md → ...gine_uk/parameters/gov/dwp/iidb/README.md
diff --git a/...e_uk/parameters/gov/dwp/IIDB/maximum.yaml → ...e_uk/parameters/gov/dwp/iidb/maximum.yaml b/...e_uk/parameters/gov/dwp/IIDB/maximum.yaml → ...e_uk/parameters/gov/dwp/iidb/maximum.yaml
diff --git a/...ngine_uk/parameters/gov/dwp/JSA/README.md → ...ngine_uk/parameters/gov/dwp/jsa/README.md b/...ngine_uk/parameters/gov/dwp/JSA/README.md → ...ngine_uk/parameters/gov/dwp/jsa/README.md
diff --git a/...ers/gov/dwp/JSA/contrib/amount_18_24.yaml → ...ers/gov/dwp/jsa/contrib/amount_18_24.yaml b/...ers/gov/dwp/JSA/contrib/amount_18_24.yaml → ...ers/gov/dwp/jsa/contrib/amount_18_24.yaml
diff --git a/...s/gov/dwp/JSA/contrib/amount_over_25.yaml → ...s/gov/dwp/jsa/contrib/amount_over_25.yaml b/...s/gov/dwp/JSA/contrib/amount_over_25.yaml → ...s/gov/dwp/jsa/contrib/amount_over_25.yaml
diff --git a/...s/gov/dwp/JSA/contrib/earn_disregard.yaml → ...s/gov/dwp/jsa/contrib/earn_disregard.yaml b/...s/gov/dwp/JSA/contrib/earn_disregard.yaml → ...s/gov/dwp/jsa/contrib/earn_disregard.yaml
diff --git a/...ov/dwp/JSA/contrib/pension_disregard.yaml → ...ov/dwp/jsa/contrib/pension_disregard.yaml b/...ov/dwp/JSA/contrib/pension_disregard.yaml → ...ov/dwp/jsa/contrib/pension_disregard.yaml
diff --git a/.../parameters/gov/dwp/JSA/hours/couple.yaml → .../parameters/gov/dwp/jsa/hours/couple.yaml b/.../parameters/gov/dwp/JSA/hours/couple.yaml → .../parameters/gov/dwp/jsa/hours/couple.yaml
diff --git a/.../parameters/gov/dwp/JSA/hours/single.yaml → .../parameters/gov/dwp/jsa/hours/single.yaml b/.../parameters/gov/dwp/JSA/hours/single.yaml → .../parameters/gov/dwp/jsa/hours/single.yaml
diff --git a/...ters/gov/dwp/JSA/income/amount_18_24.yaml → ...ters/gov/dwp/jsa/income/amount_18_24.yaml b/...ters/gov/dwp/JSA/income/amount_18_24.yaml → ...ters/gov/dwp/jsa/income/amount_18_24.yaml
diff --git a/...rs/gov/dwp/JSA/income/amount_over_25.yaml → ...rs/gov/dwp/jsa/income/amount_over_25.yaml b/...rs/gov/dwp/JSA/income/amount_over_25.yaml → ...rs/gov/dwp/jsa/income/amount_over_25.yaml
diff --git a/...parameters/gov/dwp/JSA/income/couple.yaml → ...parameters/gov/dwp/jsa/income/couple.yaml b/...parameters/gov/dwp/JSA/income/couple.yaml → ...parameters/gov/dwp/jsa/income/couple.yaml
diff --git a/...p/JSA/income/income_disregard_couple.yaml → ...p/jsa/income/income_disregard_couple.yaml b/...p/JSA/income/income_disregard_couple.yaml → ...p/jsa/income/income_disregard_couple.yaml
diff --git a/.../income/income_disregard_lone_parent.yaml → .../income/income_disregard_lone_parent.yaml b/.../income/income_disregard_lone_parent.yaml → .../income/income_disregard_lone_parent.yaml
diff --git a/...p/JSA/income/income_disregard_single.yaml → ...p/jsa/income/income_disregard_single.yaml b/...p/JSA/income/income_disregard_single.yaml → ...p/jsa/income/income_disregard_single.yaml
diff --git a/...parameters/gov/dwp/JSA/income/takeup.yaml → ...parameters/gov/dwp/jsa/income/takeup.yaml b/...parameters/gov/dwp/JSA/income/takeup.yaml → ...parameters/gov/dwp/jsa/income/takeup.yaml
diff --git a/...ngine_uk/parameters/gov/dwp/LHA/README.md → ...ngine_uk/parameters/gov/dwp/lha/README.md b/...ngine_uk/parameters/gov/dwp/LHA/README.md → ...ngine_uk/parameters/gov/dwp/lha/README.md
diff --git a/...ine_uk/parameters/gov/dwp/LHA/__init__.py → ...ine_uk/parameters/gov/dwp/lha/__init__.py b/...ine_uk/parameters/gov/dwp/LHA/__init__.py → ...ine_uk/parameters/gov/dwp/lha/__init__.py
diff --git a/...ine_uk/parameters/gov/dwp/LHA/freeze.yaml → ...ine_uk/parameters/gov/dwp/lha/freeze.yaml b/...ine_uk/parameters/gov/dwp/LHA/freeze.yaml → ...ine_uk/parameters/gov/dwp/lha/freeze.yaml
diff --git a/...ters/gov/dwp/LHA/lha_list_of_rents.csv.gz → ...ters/gov/dwp/lha/lha_list_of_rents.csv.gz b/...ters/gov/dwp/LHA/lha_list_of_rents.csv.gz → ...ters/gov/dwp/lha/lha_list_of_rents.csv.gz
diff --git a/...ov/dwp/LHA/means_test/earn_disregard.yaml → ...ov/dwp/lha/means_test/earn_disregard.yaml b/...ov/dwp/LHA/means_test/earn_disregard.yaml → ...ov/dwp/lha/means_test/earn_disregard.yaml
diff --git a/...A/means_test/income_disregard_couple.yaml → ...a/means_test/income_disregard_couple.yaml b/...A/means_test/income_disregard_couple.yaml → ...a/means_test/income_disregard_couple.yaml
diff --git a/...LHA/means_test/income_disregard_lone.yaml → ...lha/means_test/income_disregard_lone.yaml b/...LHA/means_test/income_disregard_lone.yaml → ...lha/means_test/income_disregard_lone.yaml
diff --git a/...ns_test/income_disregard_lone_parent.yaml → ...ns_test/income_disregard_lone_parent.yaml b/...ns_test/income_disregard_lone_parent.yaml → ...ns_test/income_disregard_lone_parent.yaml
diff --git a/...A/means_test/income_disregard_single.yaml → ...a/means_test/income_disregard_single.yaml b/...A/means_test/income_disregard_single.yaml → ...a/means_test/income_disregard_single.yaml
diff --git a/...dwp/LHA/means_test/pension_disregard.yaml → ...dwp/lha/means_test/pension_disregard.yaml b/...dwp/LHA/means_test/pension_disregard.yaml → ...dwp/lha/means_test/pension_disregard.yaml
diff --git a/...v/dwp/LHA/means_test/withdrawal_rate.yaml → ...v/dwp/lha/means_test/withdrawal_rate.yaml b/...v/dwp/LHA/means_test/withdrawal_rate.yaml → ...v/dwp/lha/means_test/withdrawal_rate.yaml
diff --git a/.../gov/dwp/LHA/means_test/worker_hours.yaml → .../gov/dwp/lha/means_test/worker_hours.yaml b/.../gov/dwp/LHA/means_test/worker_hours.yaml → .../gov/dwp/lha/means_test/worker_hours.yaml
diff --git a/...A/means_test/worker_income_disregard.yaml → ...a/means_test/worker_income_disregard.yaml b/...A/means_test/worker_income_disregard.yaml → ...a/means_test/worker_income_disregard.yaml
diff --git a/...uk/parameters/gov/dwp/LHA/percentile.yaml → ...uk/parameters/gov/dwp/lha/percentile.yaml b/...uk/parameters/gov/dwp/LHA/percentile.yaml → ...uk/parameters/gov/dwp/lha/percentile.yaml
diff --git a/...A/shared_accommodation_age_threshold.yaml → ...a/shared_accommodation_age_threshold.yaml b/...A/shared_accommodation_age_threshold.yaml → ...a/shared_accommodation_age_threshold.yaml
diff --git a/...means_test/income_threshold_CTC_only.yaml → ...means_test/income_threshold_ctc_only.yaml b/...means_test/income_threshold_CTC_only.yaml → ...means_test/income_threshold_ctc_only.yaml
diff --git a/...ances/personal_allowance/maximum_ANI.yaml → ...ances/personal_allowance/maximum_ani.yaml b/...ances/personal_allowance/maximum_ANI.yaml → ...ances/personal_allowance/maximum_ani.yaml
diff --git a/...hmrc/income_tax/charges/CB_HITC/README.md → ...hmrc/income_tax/charges/cb_hitc/README.md b/...hmrc/income_tax/charges/CB_HITC/README.md → ...hmrc/income_tax/charges/cb_hitc/README.md
diff --git a/...me_tax/charges/CB_HITC/phase_out_end.yaml → ...me_tax/charges/cb_hitc/phase_out_end.yaml b/...me_tax/charges/CB_HITC/phase_out_end.yaml → ...me_tax/charges/cb_hitc/phase_out_end.yaml
@@ -4,7 +4,7 @@ values:
   2024-01-01: 80_000
 metadata:
   period: year
-  name: CB_HITC_reduction_threshold
+  name: cb_hitc_reduction_threshold
   label: Child Benefit Tax Charge phase-out end
   unit: currency-GBP
   reference:

diff --git a/..._tax/charges/CB_HITC/phase_out_start.yaml → ..._tax/charges/cb_hitc/phase_out_start.yaml b/..._tax/charges/CB_HITC/phase_out_start.yaml → ..._tax/charges/cb_hitc/phase_out_start.yaml
@@ -4,7 +4,7 @@ values:
   2024-01-01: 60_000
 metadata:
   period: year
-  name: CB_HITC_reduction_threshold
+  name: cb_hitc_reduction_threshold
   label: Child Benefit Tax Charge phase-out threshold
   unit: currency-GBP
   reference:

diff --git a/policyengine_uk/parameters/gov/hmrc/income_tax/income_tax_additions.yaml b/policyengine_uk/parameters/gov/hmrc/income_tax/income_tax_additions.yaml
@@ -8,5 +8,5 @@ values:
   - savings_income_tax
   - dividend_income_tax
   - property_income_tax
-  - CB_HITC
+  - cb_hitc
   - personal_pension_contributions_tax
diff --git a/policyengine_uk/reforms/conservatives/household_based_hitc.py b/policyengine_uk/reforms/conservatives/household_based_hitc.py
@@ -1,7 +1,7 @@
 from policyengine_uk.model_api import *
 
 
-class CB_HITC(Variable):
+class cb_hitc(Variable):
     value_type = float
     entity = Person
     label = "Child Benefit High-Income Tax Charge"
@@ -12,7 +12,7 @@ class CB_HITC(Variable):
 
     def formula(person, period, parameters):
         CB_received = person.benunit("child_benefit", period)
-        hitc = parameters(period).gov.hmrc.income_tax.charges.CB_HITC
+        hitc = parameters(period).gov.hmrc.income_tax.charges.cb_hitc
         personal_income = person("adjusted_net_income", period)
         income = person.benunit.sum(personal_income)
         percentage = max_(income - hitc.phase_out_start, 0) / (
@@ -23,7 +23,7 @@ def formula(person, period, parameters):
 
 class make_cb_hitc_household_based(Variable):
     def apply(self):
-        self.update_variable(CB_HITC)
+        self.update_variable(cb_hitc)
 
 
 def create_household_based_hitc_reform(parameters, period):

diff --git a/policyengine_uk/scenarios/uc_reform.py b/policyengine_uk/scenarios/uc_reform.py
@@ -23,15 +23,15 @@ def add_universal_credit_reform(sim: Microsimulation):
         if not rebalancing.active(year):
             continue
         is_post_25_claimant = uc_seed < p_uc_post_2026_status[year]
-        current_health_element = sim.calculate("uc_LCWRA_element", year)
+        current_health_element = sim.calculate("uc_lcwra_element", year)
         # Set new claimants to £217.26/month from April 2026 (pre-2026 claimaints keep inflation-linked increases)
         # https://bills.parliament.uk/publications/62123/documents/6889#page=16
         current_health_element[
             (current_health_element > 0) & is_post_25_claimant
         ] = (
             new_claimant_health_element(year) * 12
         )  # Monthly amount * 12
-        sim.set_input("uc_LCWRA_element", year, current_health_element)
+        sim.set_input("uc_lcwra_element", year, current_health_element)
 
     # https://bills.parliament.uk/publications/62123/documents/6889#page=14
 

diff --git a/policyengine_uk/simulation.py b/policyengine_uk/simulation.py
@@ -164,8 +164,10 @@ def apply_parameter_changes(self, changes: dict):
         self.tax_benefit_system.reset_parameters()
 
         for parameter in changes:
+            # Convert parameter name to lowercase for backwards compatibility
+            parameter_lowercase = parameter.lower()
             p: Parameter = self.tax_benefit_system.parameters.get_child(
-                parameter
+                parameter_lowercase
             )
             if isinstance(changes[parameter], dict):
                 # Time-period specific changes
@@ -479,6 +481,10 @@ def calculate(
     ):
         if variable_name is None:
             return self.calculate_all()
+
+        # Convert variable name to lowercase for backwards compatibility
+        variable_name = variable_name.lower()
+
         tracer: SimpleTracer = self.tracer
         if len(tracer.stack) == 0:
             # Only decode enums to string values when we're not within

diff --git a/...eline/finance/benefit/family/housing_benefit/entitlement/housing_benefit_entitlement.yaml b/...eline/finance/benefit/family/housing_benefit/entitlement/housing_benefit_entitlement.yaml
@@ -2,10 +2,10 @@
   period: 2025
   input:
     benunit_rent: 8_000
-    LHA_eligible: false
+    lha_eligible: false
     housing_benefit_applicable_amount: 1_000
     housing_benefit_applicable_income: 11_000
-    LHA_cap: 1_000
+    lha_cap: 1_000
     housing_benefit_non_dep_deductions: 0
   output:
     housing_benefit_entitlement: 1_500
@@ -14,10 +14,10 @@
   period: 2025
   input:
     benunit_rent: 8_000
-    LHA_eligible: true
+    lha_eligible: true
     housing_benefit_applicable_amount: 1_000
     housing_benefit_applicable_income: 11_000
-    LHA_cap: 1_000
+    lha_cap: 1_000
     housing_benefit_non_dep_deductions: 0
   output:
     housing_benefit_entitlement: 1_000
@@ -26,10 +26,10 @@
   period: 2025
   input:
     benunit_rent: 8_000
-    LHA_eligible: false
+    lha_eligible: false
     housing_benefit_applicable_amount: 1_000
     housing_benefit_applicable_income: 11_000
-    LHA_cap: 1_000
+    lha_cap: 1_000
     housing_benefit_non_dep_deductions: 2_000
   output:
     housing_benefit_entitlement: 0
@@ -38,10 +38,10 @@
   period: 2025
   input:
     benunit_rent: 6_000
-    LHA_eligible: false
+    lha_eligible: false
     housing_benefit_applicable_amount: 1_000
     housing_benefit_applicable_income: 11_000
-    LHA_cap: 1_000
+    lha_cap: 1_000
     housing_benefit_non_dep_deductions: 0
   output:
     housing_benefit_entitlement: 0
diff --git a/...cy/baseline/finance/benefit/family/housing_benefit/housing_benefit_applicable_amount.yaml b/...cy/baseline/finance/benefit/family/housing_benefit/housing_benefit_applicable_amount.yaml
@@ -4,13 +4,13 @@
   input:
     people: 
       person1:
-        is_SP_age: false
+        is_sp_age: false
       person2:
-        is_SP_age: false
+        is_sp_age: false
       person3:
-        is_SP_age: false
+        is_sp_age: false
       person4:
-        is_SP_age: false
+        is_sp_age: false
     benunits:
       benunit:
         members: [person1, person2, person3, person4]
@@ -29,13 +29,13 @@
   input:
     people: 
       person1:
-        is_SP_age: false
+        is_sp_age: false
       person2:
-        is_SP_age: false
+        is_sp_age: false
       person3:
-        is_SP_age: false
+        is_sp_age: false
       person4:
-        is_SP_age: false
+        is_sp_age: false
     benunits:
       benunit:
         members: [person1, person2, person3, person4]
@@ -54,13 +54,13 @@
   input:
     people: 
       person1:
-        is_SP_age: false
+        is_sp_age: false
       person2:
-        is_SP_age: false
+        is_sp_age: false
       person3:
-        is_SP_age: false
+        is_sp_age: false
       person4:
-        is_SP_age: false
+        is_sp_age: false
     benunits:
       benunit:
         members: [person1, person2, person3, person4]
@@ -79,13 +79,13 @@
   input:
     people: 
       person1:
-        is_SP_age: false
+        is_sp_age: false
       person2:
-        is_SP_age: false
+        is_sp_age: false
       person3:
-        is_SP_age: false
+        is_sp_age: false
       person4:
-        is_SP_age: false
+        is_sp_age: false
     benunits:
       benunit:
         members: [person1, person2, person3, person4]
@@ -104,13 +104,13 @@
   input:
     people: 
       person1:
-        is_SP_age: false
+        is_sp_age: false
       person2:
-        is_SP_age: false
+        is_sp_age: false
       person3:
-        is_SP_age: false
+        is_sp_age: false
       person4:
-        is_SP_age: false
+        is_sp_age: false
     benunits:
       benunit:
         members: [person1, person2, person3, person4]
@@ -129,13 +129,13 @@
   input:
     people: 
       person1:
-        is_SP_age: false
+        is_sp_age: false
       person2:
-        is_SP_age: false
+        is_sp_age: false
       person3:
-        is_SP_age: false
+        is_sp_age: false
       person4:
-        is_SP_age: false
+        is_sp_age: false
     benunits:
       benunit:
         members: [person1, person2, person3, person4]

diff --git a/...ests/policy/baseline/finance/benefit/family/housing_benefit/housing_benefit_eligible.yaml b/...ests/policy/baseline/finance/benefit/family/housing_benefit/housing_benefit_eligible.yaml
@@ -4,7 +4,7 @@
   input:
     in_social_housing: true
     housing_benefit_reported: 1
-    LHA_eligible: false
+    lha_eligible: false
   output:
     housing_benefit_eligible: true
 
@@ -14,7 +14,7 @@
   input:
     in_social_housing: false
     housing_benefit_reported: 1
-    LHA_eligible: true
+    lha_eligible: true
   output:
     housing_benefit_eligible: true
 
@@ -24,7 +24,7 @@
   input:
     in_social_housing: false
     housing_benefit_reported: 0
-    LHA_eligible: true
+    lha_eligible: true
   output:
     housing_benefit_eligible: false
 
@@ -34,6 +34,6 @@
   input:
     in_social_housing: false
     housing_benefit_reported: 1
-    LHA_eligible: false
+    lha_eligible: false
   output:
     housing_benefit_eligible: false
diff --git a/.../baseline/finance/benefit/family/LHA.yaml → .../baseline/finance/benefit/family/lha.yaml b/.../baseline/finance/benefit/family/LHA.yaml → .../baseline/finance/benefit/family/lha.yaml
@@ -3,10 +3,10 @@
   absolute_error_margin: 20
   input:
     age: 18
-    LHA_category: C
+    lha_category: C
   output:
     brma: MAIDSTONE
-    BRMA_LHA_rate: 9_771
+    brma_lha_rate: 9_771
 - name: BRMA inputs
   period: 2020
   absolute_error_margin: 0
@@ -19,8 +19,8 @@
   absolute_error_margin: 20
   input:
     brma: GUILDFORD
-    LHA_category: C
+    lha_category: C
   output:
     brma: GUILDFORD
-    LHA_category: C
-    BRMA_LHA_rate: 13_164
+    lha_category: C
+    brma_lha_rate: 13_164