修正

backend/app/payroll/bonus/service.py

@@ -12,7 +12,7 @@ class BonusCalculationService:
     
     @staticmethod
     def get_insurance_rate(rate_type: str, target_date: date, calculation_target: str = '賞与') -> Dict[str, Any]:
-        """保険料率を取得（賞与用）"""
+        """保険料率を取得（賞与用、年度がない場合は前年度を参照）"""
         with get_connection() as conn:
             with conn.cursor() as cur:
                 # rate_yearで年度を判定
@@ -28,7 +28,28 @@ class BonusCalculationService:
                     """,
                     (rate_type, target_year, calculation_target)
                 )
-                return cur.fetchone()
+                result = cur.fetchone()
+                
+                # 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）
+                if not result:
+                    for year_offset in range(1, 4):
+                        previous_year = target_year - year_offset
+                        cur.execute(
+                            """
+                            SELECT * FROM insurance_rates 
+                            WHERE rate_type = %s
+                            AND rate_year = %s
+                            AND calculation_target = %s
+                            ORDER BY rate_id DESC
+                            LIMIT 1
+                            """,
+                            (rate_type, previous_year, calculation_target)
+                        )
+                        result = cur.fetchone()
+                        if result:
+                            break
+                
+                return result
     
     @staticmethod
     def get_insurance_limit(setting_type: str, target_date: date) -> Decimal: