298 lines
12 KiB
Python
298 lines
12 KiB
Python
"""
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賞与計算サービス (Bonus Calculation Service)
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"""
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from decimal import Decimal
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from datetime import date
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from typing import Dict, Any
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from ...core.database import get_connection
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class BonusCalculationService:
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"""賞与計算サービス"""
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@staticmethod
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def get_insurance_rate(rate_type: str, target_date: date, calculation_target: str = '賞与') -> Dict[str, Any]:
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"""保険料率を取得（賞与用、年度がない場合は前年度を参照）"""
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with get_connection() as conn:
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with conn.cursor() as cur:
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# rate_yearで年度を判定
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target_year = target_date.year
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cur.execute(
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"""
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SELECT * FROM insurance_rates
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WHERE rate_type = %s
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AND rate_year = %s
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AND calculation_target = %s
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ORDER BY rate_id DESC
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LIMIT 1
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""",
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(rate_type, target_year, calculation_target)
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)
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result = cur.fetchone()
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# 現在の年度でデータが見つからない場合は前年度を検索（最大3年遡る）
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if not result:
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for year_offset in range(1, 4):
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previous_year = target_year - year_offset
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cur.execute(
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"""
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SELECT * FROM insurance_rates
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WHERE rate_type = %s
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AND rate_year = %s
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AND calculation_target = %s
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ORDER BY rate_id DESC
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LIMIT 1
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""",
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(rate_type, previous_year, calculation_target)
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)
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result = cur.fetchone()
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if result:
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break
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return result
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@staticmethod
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def get_insurance_limit(setting_type: str, target_date: date) -> Decimal:
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"""社会保険料上限を取得"""
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with get_connection() as conn:
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with conn.cursor() as cur:
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cur.execute(
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"""
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SELECT limit_amount FROM insurance_limit_settings
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WHERE setting_type = %s
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AND valid_from <= %s
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AND (valid_to IS NULL OR valid_to >= %s)
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ORDER BY valid_from DESC
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LIMIT 1
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""",
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(setting_type, target_date, target_date)
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)
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result = cur.fetchone()
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return Decimal(str(result["limit_amount"])) if result else Decimal("0")
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@staticmethod
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def get_previous_salary_avg(employee_id: int, payment_date: date) -> Decimal:
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"""前月までの3ヶ月平均給与を取得（賞与所得税計算用）"""
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with get_connection() as conn:
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with conn.cursor() as cur:
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# 前月までの3ヶ月の総支給額を取得
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cur.execute(
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"""
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SELECT AVG(total_payment - commute_allowance) as avg_salary
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FROM (
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SELECT total_payment, commute_allowance
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FROM monthly_payroll
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WHERE employee_id = %s
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AND payment_date < %s
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AND status IN ('approved', 'paid')
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ORDER BY payment_date DESC
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LIMIT 3
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) as recent_payroll
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""",
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(employee_id, payment_date)
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)
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result = cur.fetchone()
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return Decimal(str(result["avg_salary"])) if result and result["avg_salary"] else Decimal("0")
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@staticmethod
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def calculate_bonus_income_tax(
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bonus_amount: Decimal,
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previous_salary_avg: Decimal,
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dependents_count: int
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) -> Decimal:
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"""
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賞与所得税を計算
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賞与税率 = (前月給与額 - 社会保険料) × 扶養人数に応じた税率
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"""
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# 簡易計算: 賞与額から社会保険料概算を引いた額の10.21%を所得税とする
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# 実際は前月給与から税率を求める複雑な計算が必要
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if previous_salary_avg == Decimal("0"):
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# 前月給与がない場合は賞与額の10.21%
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return (bonus_amount * Decimal("0.1021")).quantize(Decimal("1"))
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# 扶養人数による税率軽減（簡略化）
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rate = Decimal("0.1021") # 基本税率 10.21%
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if dependents_count == 1:
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rate = Decimal("0.0820") # 8.20%
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elif dependents_count == 2:
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rate = Decimal("0.0619") # 6.19%
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elif dependents_count >= 3:
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rate = Decimal("0.0418") # 4.18%
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return (bonus_amount * rate).quantize(Decimal("1"))
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@staticmethod
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def calculate_bonus(
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employee_id: int,
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bonus_year: int,
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bonus_month: int,
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bonus_type: str,
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payment_date: date,
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base_bonus: Decimal,
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performance_bonus: Decimal = Decimal("0"),
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other_bonus: Decimal = Decimal("0"),
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other_deduction: Decimal = Decimal("0"),
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calculated_by: str = "system"
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) -> Dict[str, Any]:
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"""賞与を計算"""
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# 総支給額
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total_bonus = base_bonus + performance_bonus + other_bonus
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# 社会保険料上限を取得（賞与専用の標準賞与額上限を使用）
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health_insurance_limit = BonusCalculationService.get_insurance_limit(
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"健康保険標準賞与額上限", payment_date
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)
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pension_insurance_limit = BonusCalculationService.get_insurance_limit(
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"厚生年金標準賞与額上限", payment_date
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)
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# 賞与の標準賞与額（上限適用）
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health_standard_bonus = min(total_bonus, health_insurance_limit) if health_insurance_limit > 0 else total_bonus
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pension_standard_bonus = min(total_bonus, pension_insurance_limit) if pension_insurance_limit > 0 else total_bonus
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# 従業員情報を取得（年齢計算のため）
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with get_connection() as conn:
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with conn.cursor() as cur:
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cur.execute(
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"SELECT birth_date FROM employees WHERE employee_id = %s",
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(employee_id,)
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)
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employee_info = cur.fetchone()
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# 年齢を計算（介護保険は40歳以上65歳未満が対象）
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age = 0
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if employee_info and employee_info["birth_date"]:
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birth_date = employee_info["birth_date"]
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# より正確な年齢計算
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age = payment_date.year - birth_date.year
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# 誕生日がまだ来ていない場合は-1
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if (payment_date.month, payment_date.day) < (birth_date.month, birth_date.day):
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age -= 1
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# 健康保険（賞与額の1/1000で計算）
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health_insurance_rate = BonusCalculationService.get_insurance_rate("健康保険", payment_date)
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health_insurance = Decimal("0")
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if health_insurance_rate:
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health_insurance = (
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health_standard_bonus * Decimal(str(health_insurance_rate["employee_rate"]))
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).quantize(Decimal("1"))
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# 介護保険（40歳以上65歳未満が対象）
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care_insurance = Decimal("0")
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if 40 <= age < 65:
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care_insurance_rate = BonusCalculationService.get_insurance_rate("介護保険", payment_date)
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if care_insurance_rate:
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care_insurance = (
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health_standard_bonus * Decimal(str(care_insurance_rate["employee_rate"]))
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).quantize(Decimal("1"))
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# 厚生年金
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pension_insurance_rate = BonusCalculationService.get_insurance_rate("厚生年金", payment_date)
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pension_insurance = Decimal("0")
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if pension_insurance_rate:
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pension_insurance = (
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pension_standard_bonus * Decimal(str(pension_insurance_rate["employee_rate"]))
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).quantize(Decimal("1"))
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# 雇用保険
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employment_insurance_rate = BonusCalculationService.get_insurance_rate("雇用保険", payment_date)
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employment_insurance = Decimal("0")
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if employment_insurance_rate:
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employment_insurance = (
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total_bonus * Decimal(str(employment_insurance_rate["employee_rate"]))
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).quantize(Decimal("1"))
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# 子ども・子育て支援金（令和8年4月分以降のみ適用）
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# 賞与の場合: 標準報酬月額表の淨化率を使い、total_bonus × 子育て率 / 2
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child_support = Decimal("0")
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is_child_support_applicable = (
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(bonus_year == 2026 and bonus_month >= 4) or bonus_year >= 2027
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)
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if is_child_support_applicable:
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with get_connection() as conn:
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with conn.cursor() as cur:
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# 標準報酬月額表から子育て率を取得（最上位等級rowの child_support/monthly_amountで率を計算）
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cur.execute(
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"""
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SELECT child_support, monthly_amount
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FROM standard_remuneration
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WHERE rate_year = %s
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AND monthly_amount > 0 AND child_support > 0
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ORDER BY monthly_amount DESC
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LIMIT 1
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""",
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(payment_date.year,)
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)
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sr = cur.fetchone()
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if sr and sr["monthly_amount"] and sr["monthly_amount"] > 0:
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cs_rate = Decimal(str(sr["child_support"])) / Decimal(str(sr["monthly_amount"]))
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# 標準賞与額に封上限なし（法定上賞与には標準賞与額上限なし）
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child_support = (total_bonus * cs_rate / Decimal("2")).quantize(Decimal("1"))
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print(f"[DEBUG] 賞与子育て支援金: 率={cs_rate}, 賞与総額={total_bonus} → 従業員負担={child_support}")
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# 所得税の計算（賞与特有の計算）
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from ..calculation.service import PayrollCalculationService
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dependents_count = PayrollCalculationService.get_active_dependents_count(employee_id, payment_date)
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previous_salary_avg = BonusCalculationService.get_previous_salary_avg(employee_id, payment_date)
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# 課税対象額
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taxable_bonus = (
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total_bonus -
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health_insurance -
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care_insurance -
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pension_insurance -
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employment_insurance -
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child_support
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)
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income_tax = BonusCalculationService.calculate_bonus_income_tax(
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taxable_bonus,
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previous_salary_avg,
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dependents_count
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)
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# 総控除額
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total_deduction = (
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health_insurance +
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care_insurance +
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pension_insurance +
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employment_insurance +
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child_support +
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income_tax +
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other_deduction
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)
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# 差引支給額
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net_bonus = total_bonus - total_deduction
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return {
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"employee_id": employee_id,
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"bonus_year": bonus_year,
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"bonus_month": bonus_month,
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"bonus_type": bonus_type,
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"payment_date": payment_date,
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"status": "calculated",
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# 支給項目
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"base_bonus": base_bonus,
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"performance_bonus": performance_bonus,
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"other_bonus": other_bonus,
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"total_bonus": total_bonus,
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# 控除項目
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"health_insurance": health_insurance,
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"care_insurance": care_insurance,
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"pension_insurance": pension_insurance,
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"employment_insurance": employment_insurance,
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"child_support": child_support,
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"income_tax": income_tax,
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"other_deduction": other_deduction,
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"total_deduction": total_deduction,
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# 差引支給額
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"net_bonus": net_bonus,
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"calculated_by": calculated_by
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}
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