Question about West Virginia senior citizen deduction

[martinholmer]

In the 0.639.0 version, the code for the wv_senior_citizen_disability_deduction_person variable is as follows:

policyengine-us/policyengine_us/variables/gov/states/wv/tax/income/subtractions/senior_citizen_disability_deduction/wv_senior_citizen_disability_deduction_person.py

Lines 4 to 28 in babd6ea

	class wv_senior_citizen_disability_deduction_person(Variable):
	value_type = float
	entity = Person
	label = (
	"West Virginia senior citizen or disability deduction for each person"
	)
	unit = USD
	definition_period = YEAR
	defined_for = "wv_senior_citizen_disability_deduction_eligible_person"
	def formula(person, period, parameters):
	p = parameters(
	period
	).gov.states.wv.tax.income.subtractions.senior_citizen_disability_deduction
	agi_person = person("adjusted_gross_income_person", period)
	capped_agi = min_(p.cap, agi_person)
	# While the legal code specifies that the total value of the modifications can not exceed
	# a certain amount, we can mathematically derive this condition by subtracting the modification
	# amount from the adjusted gross income as specified in subdivision (c) (9) (ii)
	total_modifications = person(
	"wv_senior_citizen_disability_deduction_total_modifications",
	period,
	)
	return max_(0, capped_agi - total_modifications)

I don't understand the logic of line 20 or the following three-line comment. The form caps at $8000 not AGI but AGI less other modifications. Because I don't understand the "we can mathematically derive this condition" business, I wonder if the logic is incorrect. Can you explain the comment to me?

[PavelMakarchuk]

@martinholmer the comment explains that we only implicitly model the following law passage:

If the amount of wv_senior_citizen_disability_deduction_total_modifications increase over $8,000 per person, that person should be ineligible.
Instead of including another parameter for the $8,000 limit and checking the modifications against that, we reduce the amount of applicable capped AGI (max $8,000) by the amount of modifications until it reaches 0.

Let me know if we are making a mistake here thinking about the cap.

[martinholmer]

@PavelMakarchuk, Thanks for the explanation in issue #3773.
I am closing this issue now given that you have provided an explanation of the code.