Use `gross_income` rather than `id_agi` in `id_income_tax_liable`

[martinholmer]

In the 0.632.0 version, the requirements for paying the ID PBF $10 tax do not correspond to what the 2021 instructions say. The instructions say a taxpayer that is not required to file an income tax is not liable for the PBF tax (and there are other reasons a taxpayer would not be PBF liable). Here are the instruction saying that:

The gross income levels above which taxpayers are required to file an income tax return are as follows:

But the code in the id_pbf_liable formula does not correspond to these instructions.

As a result of this discrepancy, there are many differences with TAXSIM35. The following case is an example:

- name: Tax unit with taxsimid 99992 in e21.its.csv and e21.ots.csv
  absolute_error_margin: 0.01
  period: 2021
  input:
    people:
      person1:
        age: 69
        employment_income: 10010
        taxable_interest_income: 11010
        ssi: 0  # not in TAXSIM35
        state_supplement: 0  # not in TAXSIM35
        wic: 0  # not in TAXSIM35
      person2:
        age: 11
        ssi: 0  # not in TAXSIM35
        state_supplement: 0  # not in TAXSIM35
        wic: 0  # not in TAXSIM35
    tax_units:
      tax_unit:
        members: [person1, person2]
        premium_tax_credit: 0  # not in TAXSIM35
        local_income_tax: 0  # not in TAXSIM35
        state_sales_tax: 0  # not in TAXSIM35
    spm_units:
      spm_unit:
        members: [person1, person2]
        snap: 0  # not in TAXSIM35
        tanf: 0  # not in TAXSIM35
    households:
      household:
        members: [person1, person2]
        state_fips: 16  # ID
  output:  # expected results from patched TAXSIM35 2024-01-27 version
    id_income_tax: -210.00

PEUS fails this test because it calculates the id_income_tax amount as -220 dollars, which is the size of the refundable grocery credit for this case.

[MaxGhenis]

Thanks Martin. The table corresponds to the federal standard deduction. The bug is in using AGI instead of gross income to determine whether one needs to file taxes:

policyengine-us/policyengine_us/variables/gov/states/id/tax/income/id_income_tax_liable.py

Line 13 in dc321b6

agi = tax_unit("id_agi", period)

In particular, for this case, their gross income is $21,020, which exceeds their standard deduction of $20,500 as an aged head of household, but they will be eligible for the id_aged_or_disabled_deduction, a $1,000 subtraction that goes into id_agi.

[PavelMakarchuk]

Thanks Martin. The table corresponds to the federal standard deduction. The bug is in using AGI instead of gross income to determine whether one needs to file taxes:

policyengine-us/policyengine_us/variables/gov/states/id/tax/income/id_income_tax_liable.py

Line 13 in dc321b6

agi = tax_unit("id_agi", period)

In particular, for this case, their gross income is $21,020, which exceeds their standard deduction of $20,500 as an aged head of household, but they will be eligible for the id_aged_or_disabled_deduction, a $1,000 subtraction that goes into id_agi.

also needed to add the PDF after the non-refundable credits were subtracted