austax: Implement Medicare levy reduction

austax/reports.py

@@ -20,7 +20,7 @@ from drcr.models import AccountConfiguration, Amount, Metadata, Transaction, Tri
 from drcr.reports import Calculated, Report, Section, Spacer, Subtotal, entries_for_kind
 from drcr.webapp import eofy_date, sofy_date
 
-from .tax_tables import base_tax, repayment_rates, fbt_grossup
+from .tax_tables import base_tax, medicare_levy_threshold, repayment_rates, fbt_grossup
 
 def base_income_tax(year, taxable_income):
 	"""Get the amount of base income tax"""
@@ -42,10 +42,17 @@ def lito(taxable_income):
 	
 	return Amount(0, '$')
 
-def medicare_levy(taxable_income):
-	if taxable_income.quantity < 2920700:
-		raise NotImplementedError('Medicare levy reduction is not implemented')
+def medicare_levy(year, taxable_income):
+	lower_threshold, upper_threshold = medicare_levy_threshold[year]
 	
+	if taxable_income.quantity < lower_threshold * 100:
+		return Amount(0, '$')
+	
+	if taxable_income.quantity < upper_threshold * 100:
+		# Medicare levy is 10% of the amount above the lower threshold
+		return Amount((taxable_income - lower_threshold * 100) * 0.1, '$')
+	
+	# Normal Medicare levy
 	return Amount(int(taxable_income.quantity * 0.02), '$')
 
 def study_loan_repayment(year, taxable_income, rfb_grossedup):
@@ -153,7 +160,7 @@ def tax_summary_report():
 						),
 						Calculated(
 							'Medicare levy',
-							lambda _: medicare_levy(report.by_id('taxable').amount)
+							lambda _: medicare_levy(eofy_date().year, report.by_id('taxable').amount)
 						),
 						Subtotal('Total income tax', id='total_tax', bordered=True)
 					]

austax/tax_tables.py

@@ -82,6 +82,14 @@ repayment_rates = {
 	]
 }
 
+# Medicare levy thresholds
+# https://www.ato.gov.au/Individuals/Medicare-and-private-health-insurance/Medicare-levy/Medicare-levy-reduction/Medicare-levy-reduction-for-low-income-earners/
+# Maps each financial year to list of (lower threshold, upper threshold)
+medicare_levy_threshold = {
+	2023: (24276, 30345),
+	2022: (23365, 29207)
+}
+
 # FBT type 1 gross-up factor
 # https://www.ato.gov.au/rates/fbt/#GrossupratesforFBT
 fbt_grossup = {