Refactor and add missing income tests

CHANGELOG.md

@@ -1,5 +1,53 @@
 # Changelog
 
+## 21.0.0 - [59](https://github.com/digitalaotearoa/openfisca-aotearoa/pull/59)
+
+* Tax and benefit system evolution.
+* Impacted periods: all.
+* Impacted areas: `sole_parent_support`, `jobseeker_support`
+* Details:
+  - Add `income_test_n` as the result of applying an income test to a benefit.
+
+#### Discussion
+
+Main benefits are income-tested (subject to an abatement rate based on income).
+Non-main benefits can be income-tested via main benefits (i.e. accommodation
+supplement via jobseeker). However, some benefits change the definitions of
+certain things, i.e. income is not the same for accommodation supplement and
+for jobseeker support. Furthermore, the notion of income-tested benefit has
+been replaced with that of main benefit, which can create confusion when a
+benefit like accommodation supplement is income-tested via jobseeker support.
+
+This poses a challenge to the rule-maker, because in order to define a general
+rule for an income test, that applies to benefits with different definitions of
+income, it has to make it _high order_. In plain English, it has to create a
+_rule factory_. A rule that creates a rule, depending on the context of its
+application (i.e. the benefit it is applied to).
+
+There are several ways to solve this problem, yet all gravitate around two
+philosophies:
+
+1. Stick to the letter: if the rule-maker defines a _pure high-order function_
+   that can't be applied directly, one solution is to just model it as close to
+   the letter that is possible.
+
+2. Incorporate: if the rule can't be applied directly, ignore it, and
+   incorporate it as many times as is used without abstracting it into a rule
+   the way the rule-maker did (cf. copy-paste several times).
+
+Currently the OpenFisca DSL does not provide any native way of modelling this
+cases, as it is assumed as an invariant that, what can be modelled, can be
+directly applied at definition time (just following the text), and not at
+run time (depending on the context it is being applied).
+
+As usually the law doesn't contain this kind of abstractions, their use has
+always been discouraged as _not being truthful to the text_ or _modelling as a
+developer and not as a policy folk_. This case is, then, peculiar.
+
+The solution adopted here is to model the income test as a normal `Variable`,
+and capturing the context of its application from the stack. While it works,
+it is not a very elegant solution, and it is likely error-prone.
+
 ### 20.1.1 - [48](https://github.com/digitalaotearoa/openfisca-aotearoa/pull/48)
 
 * Test case.

CONTRIBUTING.md

@@ -275,12 +275,10 @@ This project currently utilises one specific pattern however for benefit calcula
 - `jobseeker_support__entitled` (true/false) - or - `jobseeker_support__eligible` (true/false)
 - `jobseeker_support__base` (float)
 - `jobseeker_support__cutoff` (float)
-- `jobseeker_support__reduction` (float)
+- `jobseeker_support__abatement` (float)
 - `jobseeker_support__benefit` (float)
 
 i.e. the formula for `jobseeker_support__benefit` would be:
  ```
- jobseeker_support__entitled * min(jobseeker_support__base - jobseeker_support__reduction, jobseeker_support__cutoff)
+ jobseeker_support__entitled * min(jobseeker_support__base - jobseeker_support__abatement, jobseeker_support__cutoff)
  ```
-
-

openfisca_aotearoa/parameters/social_security/income_test_1.yaml → openfisca_aotearoa/parameters/social_security/dictionary/income_test_1.yaml

@@ -1,9 +1,16 @@
-description: Social Security Income Test 1
+description: >
+    Social Security Act 2018 -
+    Schedule 2 Dictionary -
+    Income test 1 -
+    The applicable rate of benefit must be reduced—
+      (a) by 30 cents for every $1 of the total income of the beneficiary and
+          the beneficiary’s spouse or partner that is more than $160 a week but
+          not more than $250 a week
+      (b) by 70 cents for every $1 of that income that is more than $250 a week
 metadata:
-# currency or /1 (rate) or year (never used)
-  unit: currency
-# single_amount or marginal_rate or marginal_amount or value?
-  type: value
+  type: marginal_rate
+  rate_unit: /1
+  threshold_unit: currency-NZD
   reference:
     2018-11-26:
       title: Social Security Act 2018 (as enacted)
@@ -17,33 +24,43 @@ metadata:
 brackets:
   - rate:
       2018-11-26:
-        value: 0
+        value: 0.0
+      2020-04-01:
+        value: 0.0
+      2021-04-01:
+        value: 0.0
     threshold:
       2018-11-26:
         value: 0
+      2020-04-01:
+        value: 0
+      2021-04-01:
+        value: 0
   - rate:
       2018-11-26:
         value: 0.3
+      2020-04-01:
+        value: 0.3
+      2021-04-01:
+        value: 0.3
     threshold:
       2018-11-26:
         value: 100
       2020-04-01:
         value: 115
       2021-04-01:
         value: 160
-      # no change in 2022
-      # no change in 2023
-      # https://www.legislation.govt.nz/all/results.aspx?search=ad_act%40bill%40regulation%40deemedreg__%22Income+Test+1%22____25_ac%40bc%40rc%40dc%40apub%40aloc%40apri%40apro%40aimp%40bgov%40bloc%40bpri%40bmem%40rpub%40rimp_ac%40bc%40rc%40ainf%40anif%40bcur%40rinf%40rnif%40raif%40rasm%40rrev_a_aw_se_&p=1
   - rate:
       2018-11-26:
         value: 0.7
+      2020-04-01:
+        value: 0.7
+      2021-04-01:
+        value: 0.7
     threshold:
       2018-11-26:
         value: 200
       2020-04-01:
         value: 215
       2021-04-01:
         value: 250
-      # no change in 2022
-      # no change in 2023
-      # https://www.legislation.govt.nz/all/results.aspx?search=ad_act%40bill%40regulation%40deemedreg__%22Income+Test+1%22____25_ac%40bc%40rc%40dc%40apub%40aloc%40apri%40apro%40aimp%40bgov%40bloc%40bpri%40bmem%40rpub%40rimp_ac%40bc%40rc%40ainf%40anif%40bcur%40rinf%40rnif%40raif%40rasm%40rrev_a_aw_se_&p=1

openfisca_aotearoa/parameters/social_security/income_test_2.yaml → openfisca_aotearoa/parameters/social_security/dictionary/income_test_2.yaml

@@ -1,9 +1,16 @@
-description: Social Security Income Test 2
+description: >
+    Social Security Act 2018 -
+    Schedule 2 Dictionary -
+    Income test 2 -
+    The applicable rate of benefit must be reduced—
+      (a) by 15 cents for every $1 of the total income of the beneficiary and
+          the beneficiary’s spouse or partner that is more than $160 a week but
+          not more than $250 a week; and
+      (b) by 35 cents for every $1 of that income that is more than $250 a week
 metadata:
-# currency or /1 (rate) or year (never used)
-  unit: currency
-# single_amount or marginal_rate or marginal_amount or value?
-  type: value
+  type: marginal_rate
+  rate_unit: /1
+  threshold_unit: currency-NZD
   reference:
     2018-11-26:
       title: Social Security Act 2018 (as enacted)

openfisca_aotearoa/parameters/social_security/income_test_3b.yaml → openfisca_aotearoa/parameters/social_security/dictionary/income_test_3b.yaml

@@ -1,9 +1,15 @@
-description: Social Security Income Test 3b
+description: >
+    Social Security Act 2018 -
+    Schedule 2 Dictionary -
+    Income test 3 b -
+    The applicable rate of benefit must be reduced by 70 cents for every $1 of
+    total income of the beneficiary and the beneficiary’s spouse or partner
+    that is more than,— [...]
+      (b) in any other case, $160 a week
 metadata:
-# currency or /1 (rate) or year (never used)
-  unit: currency
-# single_amount or marginal_rate or marginal_amount or value?
-  type: value
+  type: marginal_rate
+  rate_unit: /1
+  threshold_unit: currency-NZD
   reference:
     2018-11-26:
       title: Social Security Act 2018 (as enacted)
@@ -31,10 +37,3 @@ brackets:
         value: 90
       2021-04-01:
         value: 160
-# Income Test 3 means that the applicable rate of benefit must be reduced by 70
-# cents for every $1 of total income of the beneficiary and the beneficiary’s
-# spouse or partner that is more than,—
-# (a) if the rate of benefit is a rate of New Zealand superannuation stated in
-#     clause 1 of Part 2 of Schedule 1 of the New Zealand Superannuation and
-#     Retirement Income Act 2001, $160 a week; or
-# (b) in any other case, $160 a week

openfisca_aotearoa/parameters/social_security/income_test_4.yaml → openfisca_aotearoa/parameters/social_security/dictionary/income_test_4.yaml

@@ -1,9 +1,14 @@
-description: Social Security Income Test 4
+description: >
+    Social Security Act 2018 -
+    Schedule 2 Dictionary -
+    Income test 4 -
+    The applicable rate of benefit must be reduced by 35 cents for every $1 of
+    the total income of the beneficiary and the beneficiary’s spouse or partner
+    that is more than $160 a week
 metadata:
-# currency or /1 (rate) or year (never used)
-  unit: currency
-# single_amount or marginal_rate or marginal_amount or value?
-  type: value
+  type: marginal_rate
+  rate_unit: /1
+  threshold_unit: currency-NZD
   reference:
     2018-11-26:
       title: Social Security Act 2018 (as enacted)

openfisca_aotearoa/tests/social_security/jobseeker_support/abatement.yaml

@@ -0,0 +1,59 @@
+- name: >
+    Social Security Act 2018 -
+    Schedule 2 Dictionary -
+    Income test 1 -
+    The applicable rate of benefit must be reduced—
+      (a) by 30 cents for every $1 of the total income of the beneficiary and
+          the beneficiary’s spouse or partner that is more than $160 a week but
+          not more than $250 a week
+      (b) by 70 cents for every $1 of that income that is more than $250 a week
+  period: 2018-11-26
+  input:
+    jobseeker_support__income:
+      2023-W01: [159.99, 160.00, 160.01, 161.99, 249.99, 250.00, 250.01, 251.99]
+    schedule_4__part1_1_c:
+      2023-W01: [true, true, true, true, true, true, true, true]
+  output:
+    jobseeker_support__abatement:
+      2023-W01: [0, 0, 0, 0.30, 26.70, 27.00, 27.00, 27.70]
+
+
+- name: >
+    Social Security Act 2018 -
+    Schedule 2 Dictionary -
+    Income test 3 -
+    The applicable rate of benefit must be reduced by 70 cents for every $1 of
+    the total income of the beneficiary and the beneficiary’s spouse or partner
+    that is more than,—
+      (b) [...] $160 a week
+  period: 2018-11-26
+  input:
+    jobseeker_support__income:
+      2023-W01: [159.99, 160.00, 160.01, 161.99, 249.99, 250.00, 250.01, 251.99]
+    schedule_4__part1_1_a:
+      2023-W01: [true, true, true, true, true, true, true, true]
+  output:
+    jobseeker_support__abatement:
+      2023-W01: [0, 0, 0, 0.70, 62.30, 63.00, 63.00, 63.70]
+
+
+- name: >
+    Social Security Act 2018 -
+    Schedule 2 Dictionary -
+    Income test 4 -
+    The applicable rate of benefit must be reduced by 35 cents for every $1 of
+    the total income of the beneficiary and the beneficiary’s spouse or partner
+    that is more than $160 a week
+  period: 2018-11-26
+  input:
+    jobseeker_support__income:
+      2023-W01: [159.99, 160.00, 160.01, 161.99, 249.99, 250.00, 250.01, 251.99]
+    schedule_4__part1_1_d:
+      2023-W01: [false, false, false, false, false, false, false, false]
+    schedule_4__part1_1_g:
+      2023-W01: [true, true, true, true, true, true, true, true]
+  output:
+    jobseeker_support__abatement:
+      2023-W01: [0, 0, 0, 0.35, 31.15, 31.50, 31.50, 31.85]
+    schedule_4__part1_1_d:
+      2023-W01: [false, false, false, false, false, false, false, false]

openfisca_aotearoa/tests/social_security/jobseeker_support/base.yaml

@@ -216,13 +216,6 @@
       2022-W01: [240.65, 406.78, 239.70]
       2023-W01: [283.00, 440.96, 274.37]
       2023-W15: [303.43, 472.79, 294.18]
-    jobseeker_support__reduction:
-      2020-W01: [143.5, 0, 0]
-      2021-W01: [59.5, 0, 0]
-      2021-W23: [0, 0, 0]
-      2022-W01: [138.6, 0, 0]
-      2023-W01: [31.5, 0, 0]
-      2023-W15: [31.5, 0, 0]
     jobseeker_support__benefit:
       2020-W01: [52, 0, 0]
       2021-W01: [154.53, 0, 0]

openfisca_aotearoa/tests/social_security/jobseeker_support/income.yaml

@@ -0,0 +1,53 @@
+- name: >
+    Social Security Act 2018 -
+    Schedule 2 Dictionary -
+    Income test 1-4 -
+    The applicable rate of benefit must be reduced [...] of the total income of
+    the beneficiary and the beneficiary’s spouse or partner.
+  period: 2018-11-26
+  input:
+    persons:
+      Vrenda:
+        social_security__income:
+          2023-W01: 0
+          2023-W02: 100
+          2023-W03: 100
+      Piedad:
+        social_security__income:
+          2023-W01: 0
+          2023-W02: 0
+          2023-W03: 100
+  output:
+    jobseeker_support__income:
+      2023-W01: [0, 0]
+      2023-W02: [100, 0]
+      2023-W03: [100, 100]
+
+
+- name: >
+    Social Security Act 2018 -
+    Schedule 2 Dictionary -
+    Income test 1-4 -
+    The applicable rate of benefit must be reduced [...] of the total income of
+    the beneficiary and the beneficiary’s spouse or partner.
+  period: 2018-11-26
+  input:
+    persons:
+      Vrenda:
+        social_security__income:
+          2023-W01: 0
+          2023-W02: 100
+          2023-W03: 100
+      Piedad:
+        social_security__income:
+          2023-W01: 0
+          2023-W02: 0
+          2023-W03: 100
+    family:
+      principal: Vrenda
+      partners: [Piedad]
+  output:
+    jobseeker_support__income:
+      2023-W01: [0, 0]
+      2023-W02: [100, 100]
+      2023-W03: [200, 200]