diff --git a/TaxBaik.Application.Tests/BusinessDayCalculatorTests.cs b/TaxBaik.Application.Tests/BusinessDayCalculatorTests.cs
index bd3f9e0..010ef98 100644
--- a/TaxBaik.Application.Tests/BusinessDayCalculatorTests.cs
+++ b/TaxBaik.Application.Tests/BusinessDayCalculatorTests.cs
@@ -8,9 +8,10 @@ public class BusinessDayCalculatorTests
     [Theory]
     [InlineData(2026, 2, 14, 2026, 2, 19)]
     [InlineData(2026, 8, 15, 2026, 8, 18)]
-    [InlineData(2026, 9, 24, 2026, 9, 28)]
     [InlineData(2026, 10, 3, 2026, 10, 6)]
+    [InlineData(2026, 9, 24, 2026, 9, 28)]
     [InlineData(2027, 2, 6, 2027, 2, 10)]
+    [InlineData(2027, 10, 9, 2027, 10, 12)]
     public void GetEffectiveDueDate_SkipsWeekendHolidayAndSubstituteHoliday(
         int dueYear, int dueMonth, int dueDay,
         int expectedYear, int expectedMonth, int expectedDay)