From b11de7e2949e9ac9b31c4b0c660fe77eea24e6e1 Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?=EA=B9=80=EB=B3=B4=EA=B3=A4?=
 <lightone2017@codebridge-x.com>
Date: Fri, 27 Feb 2026 14:10:25 +0900
Subject: [PATCH] =?UTF-8?q?fix:=20[payroll]=20=EA=B3=B5=EC=A0=9C=20?=
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- 건강보험, 장기요양보험, 국민연금, 고용보험: round() → floor(x/10)*10
- 고소득 구간 근로소득세 공식 계산도 10원 단위 절삭 적용
- 지방소득세는 이전 커밋에서 이미 적용됨
---
 app/Services/HR/PayrollService.php | 44 +++++++++++++-----------------
 1 file changed, 19 insertions(+), 25 deletions(-)

diff --git a/app/Services/HR/PayrollService.php b/app/Services/HR/PayrollService.php
index 58cfc28a..8d787e5a 100644
--- a/app/Services/HR/PayrollService.php
+++ b/app/Services/HR/PayrollService.php
@@ -504,33 +504,27 @@ private function calculateHighIncomeTax(int $salaryThousand, int $familyCount):
         $excessWon = $excessThousand * 1000;
 
         if ($salaryThousand <= 14000) {
-            return (int) ($baseTax + ($excessWon * 0.98 * 0.35) + 25000);
-        }
-        if ($salaryThousand <= 28000) {
+            $tax = $baseTax + ($excessWon * 0.98 * 0.35) + 25000;
+        } elseif ($salaryThousand <= 28000) {
             $excessWon = ($salaryThousand - 14000) * 1000;
-
-            return (int) ($baseTax + 1397000 + ($excessWon * 0.98 * 0.38));
-        }
-        if ($salaryThousand <= 30000) {
+            $tax = $baseTax + 1397000 + ($excessWon * 0.98 * 0.38);
+        } elseif ($salaryThousand <= 30000) {
             $excessWon = ($salaryThousand - 28000) * 1000;
-
-            return (int) ($baseTax + 6610600 + ($excessWon * 0.98 * 0.40));
-        }
-        if ($salaryThousand <= 45000) {
+            $tax = $baseTax + 6610600 + ($excessWon * 0.98 * 0.40);
+        } elseif ($salaryThousand <= 45000) {
             $excessWon = ($salaryThousand - 30000) * 1000;
-
-            return (int) ($baseTax + 7394600 + ($excessWon * 0.40));
-        }
-        if ($salaryThousand <= 87000) {
+            $tax = $baseTax + 7394600 + ($excessWon * 0.40);
+        } elseif ($salaryThousand <= 87000) {
             $excessWon = ($salaryThousand - 45000) * 1000;
-
-            return (int) ($baseTax + 13394600 + ($excessWon * 0.42));
+            $tax = $baseTax + 13394600 + ($excessWon * 0.42);
+        } else {
+            // 87,000천원 초과
+            $excessWon = ($salaryThousand - 87000) * 1000;
+            $tax = $baseTax + 31034600 + ($excessWon * 0.45);
         }
 
-        // 87,000천원 초과
-        $excessWon = ($salaryThousand - 87000) * 1000;
-
-        return (int) ($baseTax + 31034600 + ($excessWon * 0.45));
+        // 10원 단위 절삭
+        return (int) (floor($tax / 10) * 10);
     }
 
     /**
@@ -538,7 +532,7 @@ private function calculateHighIncomeTax(int $salaryThousand, int $familyCount):
      */
     private function calculateHealthInsurance(float $grossSalary, PayrollSetting $settings): int
     {
-        return (int) round($grossSalary * ($settings->health_insurance_rate / 100));
+        return (int) (floor($grossSalary * ($settings->health_insurance_rate / 100) / 10) * 10);
     }
 
     /**
@@ -548,7 +542,7 @@ private function calculateLongTermCare(float $grossSalary, PayrollSetting $setti
     {
         $healthInsurance = $grossSalary * ($settings->health_insurance_rate / 100);
 
-        return (int) round($healthInsurance * ($settings->long_term_care_rate / 100));
+        return (int) (floor($healthInsurance * ($settings->long_term_care_rate / 100) / 10) * 10);
     }
 
     /**
@@ -558,7 +552,7 @@ private function calculatePension(float $grossSalary, PayrollSetting $settings):
     {
         $base = min(max($grossSalary, (float) $settings->pension_min_salary), (float) $settings->pension_max_salary);
 
-        return (int) round($base * ($settings->pension_rate / 100));
+        return (int) (floor($base * ($settings->pension_rate / 100) / 10) * 10);
     }
 
     /**
@@ -566,7 +560,7 @@ private function calculatePension(float $grossSalary, PayrollSetting $settings):
      */
     private function calculateEmploymentInsurance(float $grossSalary, PayrollSetting $settings): int
     {
-        return (int) round($grossSalary * ($settings->employment_insurance_rate / 100));
+        return (int) (floor($grossSalary * ($settings->employment_insurance_rate / 100) / 10) * 10);
     }
 
     /**