Key Illinois HBWD premium bands at the chart's band starts

changelog.d/il-hbwd-premium-band-edges.fixed.md

@@ -0,0 +1 @@
+Key the Illinois Health Benefits for Workers with Disabilities premium bands at the chart's band starts, so income of exactly $250, $500 and so on pays the lower band's premium.

policyengine_us/parameters/gov/states/il/hfs/hbwd/premium/earned.yaml

@@ -6,91 +6,98 @@ metadata:
   period: month
   label: Illinois HBWD earned income premium component
   reference:
-    # Illinois presents the table as a matrix, but the values can be summed between row 1 and column 1.
-    - title: 89 Ill. Admin. Code § 120.510 (n)
+    # Summing the first column (earned) and first row (unearned) reproduces 434 of the 441
+    # cells in 120.510(n)(3); see issue 10471 for the others.
+    # Thresholds are the chart's band starts (0-250, 251-500, ..., 4751-5000, 5000+), so income of
+    # exactly $250 stays in the first band; $5,000 falls in the 4751-5000 band.
+    # Bands start at whole dollars, so income with cents stays in the band of its whole-dollar
+    # amount, as IDHS PM 15-04-03 drops cents.
+    - title: 89 Ill. Admin. Code § 120.510(n)(3)
       href: https://www.law.cornell.edu/regulations/illinois/Ill-Admin-Code-tit-89-SS-120.510
+    - title: Illinois HFS, Health Benefits for Workers with Disabilities Premium Chart
+      href: https://hfs.illinois.gov/content/dam/soi/en/web/hfs/medicalprograms/hbwd/documents/hfsweb004.pdf
 brackets:
   - threshold:
       2022-04-01: 0
     amount:
       2022-04-01: 0
   - threshold:
-      2022-04-01: 250
+      2022-04-01: 251
     amount:
       2022-04-01: 6
   - threshold:
-      2022-04-01: 500
+      2022-04-01: 501
     amount:
       2022-04-01: 13
   - threshold:
-      2022-04-01: 750
+      2022-04-01: 751
     amount:
       2022-04-01: 19
   - threshold:
-      2022-04-01: 1_000
+      2022-04-01: 1_001
     amount:
       2022-04-01: 25
   - threshold:
-      2022-04-01: 1_250
+      2022-04-01: 1_251
     amount:
       2022-04-01: 31
   - threshold:
-      2022-04-01: 1_500
+      2022-04-01: 1_501
     amount:
       2022-04-01: 38
   - threshold:
-      2022-04-01: 1_750
+      2022-04-01: 1_751
     amount:
       2022-04-01: 44
   - threshold:
-      2022-04-01: 2_000
+      2022-04-01: 2_001
     amount:
       2022-04-01: 50
   - threshold:
-      2022-04-01: 2_250
+      2022-04-01: 2_251
     amount:
       2022-04-01: 56
   - threshold:
-      2022-04-01: 2_500
+      2022-04-01: 2_501
     amount:
       2022-04-01: 63
   - threshold:
-      2022-04-01: 2_750
+      2022-04-01: 2_751
     amount:
       2022-04-01: 69
   - threshold:
-      2022-04-01: 3_000
+      2022-04-01: 3_001
     amount:
       2022-04-01: 75
   - threshold:
-      2022-04-01: 3_250
+      2022-04-01: 3_251
     amount:
       2022-04-01: 81
   - threshold:
-      2022-04-01: 3_500
+      2022-04-01: 3_501
     amount:
       2022-04-01: 88
   - threshold:
-      2022-04-01: 3_750
+      2022-04-01: 3_751
     amount:
       2022-04-01: 94
   - threshold:
-      2022-04-01: 4_000
+      2022-04-01: 4_001
     amount:
       2022-04-01: 100
   - threshold:
-      2022-04-01: 4_250
+      2022-04-01: 4_251
     amount:
       2022-04-01: 106
   - threshold:
-      2022-04-01: 4_500
+      2022-04-01: 4_501
     amount:
       2022-04-01: 113
   - threshold:
-      2022-04-01: 4_750
+      2022-04-01: 4_751
     amount:
       2022-04-01: 119
   - threshold:
-      2022-04-01: 5_000
+      2022-04-01: 5_001
     amount:
       2022-04-01: 125

policyengine_us/parameters/gov/states/il/hfs/hbwd/premium/unearned.yaml

@@ -6,91 +6,98 @@ metadata:
   period: month
   label: Illinois HBWD unearned income premium component
   reference:
-    # Illinois presents the table as a matrix, but the values can be summed between row 1 and column 1.
-    - title: 89 Ill. Admin. Code § 120.510 (n)
+    # Summing the first column (earned) and first row (unearned) reproduces 434 of the 441
+    # cells in 120.510(n)(3); see issue 10471 for the others.
+    # Thresholds are the chart's band starts (0-250, 251-500, ..., 4751-5000, 5000+), so income of
+    # exactly $250 stays in the first band; $5,000 falls in the 4751-5000 band.
+    # Bands start at whole dollars, so income with cents stays in the band of its whole-dollar
+    # amount, as IDHS PM 15-04-03 drops cents.
+    - title: 89 Ill. Admin. Code § 120.510(n)(3)
       href: https://www.law.cornell.edu/regulations/illinois/Ill-Admin-Code-tit-89-SS-120.510
+    - title: Illinois HFS, Health Benefits for Workers with Disabilities Premium Chart
+      href: https://hfs.illinois.gov/content/dam/soi/en/web/hfs/medicalprograms/hbwd/documents/hfsweb004.pdf
 brackets:
   - threshold:
       2022-04-01: 0
     amount:
       2022-04-01: 0
   - threshold:
-      2022-04-01: 250
+      2022-04-01: 251
     amount:
       2022-04-01: 19
   - threshold:
-      2022-04-01: 500
+      2022-04-01: 501
     amount:
       2022-04-01: 38
   - threshold:
-      2022-04-01: 750
+      2022-04-01: 751
     amount:
       2022-04-01: 56
   - threshold:
-      2022-04-01: 1_000
+      2022-04-01: 1_001
     amount:
       2022-04-01: 75
   - threshold:
-      2022-04-01: 1_250
+      2022-04-01: 1_251
     amount:
       2022-04-01: 94
   - threshold:
-      2022-04-01: 1_500
+      2022-04-01: 1_501
     amount:
       2022-04-01: 113
   - threshold:
-      2022-04-01: 1_750
+      2022-04-01: 1_751
     amount:
       2022-04-01: 131
   - threshold:
-      2022-04-01: 2_000
+      2022-04-01: 2_001
     amount:
       2022-04-01: 150
   - threshold:
-      2022-04-01: 2_250
+      2022-04-01: 2_251
     amount:
       2022-04-01: 169
   - threshold:
-      2022-04-01: 2_500
+      2022-04-01: 2_501
     amount:
       2022-04-01: 188
   - threshold:
-      2022-04-01: 2_750
+      2022-04-01: 2_751
     amount:
       2022-04-01: 206
   - threshold:
-      2022-04-01: 3_000
+      2022-04-01: 3_001
     amount:
       2022-04-01: 225
   - threshold:
-      2022-04-01: 3_250
+      2022-04-01: 3_251
     amount:
       2022-04-01: 244
   - threshold:
-      2022-04-01: 3_500
+      2022-04-01: 3_501
     amount:
       2022-04-01: 263
   - threshold:
-      2022-04-01: 3_750
+      2022-04-01: 3_751
     amount:
       2022-04-01: 281
   - threshold:
-      2022-04-01: 4_000
+      2022-04-01: 4_001
     amount:
       2022-04-01: 300
   - threshold:
-      2022-04-01: 4_250
+      2022-04-01: 4_251
     amount:
       2022-04-01: 319
   - threshold:
-      2022-04-01: 4_500
+      2022-04-01: 4_501
     amount:
       2022-04-01: 338
   - threshold:
-      2022-04-01: 4_750
+      2022-04-01: 4_751
     amount:
       2022-04-01: 356
   - threshold:
-      2022-04-01: 5_000
+      2022-04-01: 5_001
     amount:
       2022-04-01: 375

policyengine_us/tests/policy/baseline/gov/states/il/hfs/hbwd/il_hbwd_person.yaml

@@ -7,11 +7,11 @@
     il_hbwd_countable_earned_income: 1_000
     il_hbwd_countable_unearned_income: 1_200
   output:
-    il_hbwd_person: -100
-    # Premium: $100 (earned $25 + unearned $75)
-    # Earned $1,000 → bracket 4 → $25
-    # Unearned $1,200 → bracket 4 → $75
-    # Benefit: -$100 (cost to individual)
+    il_hbwd_person: -94
+    # Premium: $94 (earned $19 + unearned $75)
+    # Earned $1,000 → 751-1000 band → $19
+    # Unearned $1,200 → 1001-1250 band → $75
+    # Benefit: -$94 (cost to individual)
 
 - name: Case 2, HBWD person not eligible.
   period: 2024-01
@@ -31,4 +31,4 @@
     il_hbwd_countable_unearned_income: 0
   output:
     il_hbwd_person: 0
-    # Both income in first bracket → $0 premium
+    # Both incomes in the 0-250 band → $0 premium