diff --git a/utils/time.go b/utils/time.go
index 10e88a4..3d27626 100644
--- a/utils/time.go
+++ b/utils/time.go
@@ -14,16 +14,11 @@ func VeryEndOfDate(date time.Time) time.Time {
 
 func DifferenceInMonth(t1, t2 time.Time) int {
 	var differYear, differMonth int
-	if t1.After(t2) {
-		differYear = t1.Year() - t2.Year()
-		differMonth = int(t1.Month() - t2.Month())
-	} else {
-		differYear = t2.Year() - t1.Year()
-		differMonth = int(t2.Month() - t1.Month())
-	}
+	differYear = t1.Year() - t2.Year()
+	differMonth = int(t1.Month() - t2.Month())
 	return differYear*12 + differMonth
 }
 
 func IsNextMonth(t1, t2 time.Time) bool {
-	return DifferenceInMonth(t1, t2) == 1
+	return DifferenceInMonth(t1, t2) == -1
 }