diff --git a/src/main/java/com/example/fiurinee/domain/anniversary/service/AnniversaryService.java b/src/main/java/com/example/fiurinee/domain/anniversary/service/AnniversaryService.java
index 61fc2fc..cd97df4 100644
--- a/src/main/java/com/example/fiurinee/domain/anniversary/service/AnniversaryService.java
+++ b/src/main/java/com/example/fiurinee/domain/anniversary/service/AnniversaryService.java
@@ -40,6 +40,12 @@ public Anniversary addAnniversary(Long memberId, AnniversaryRequestDTO requestDT
             throw new IllegalArgumentException("Invalid anniversary type");
         }
 
+        LocalDate requestDate = requestDTO.getDate();
+        LocalDate currentDate = LocalDate.now(ZoneId.of("UTC"));
+        if (requestDate.isAfter(currentDate)) {
+            throw new IllegalArgumentException("Date cannot be in the future");
+        }
+
         ZonedDateTime zonedDateTime = requestDTO.getDate().atStartOfDay(ZoneId.of("UTC"));
         Timestamp timestamp = Timestamp.from(zonedDateTime.toInstant());
 
@@ -63,6 +69,12 @@ public Anniversary updateAnniversary(Long memberId, Long anniversaryId, Annivers
 
         validateAnniversaryType(requestDTO.getType());
 
+        LocalDate requestDate = requestDTO.getDate();
+        LocalDate currentDate = LocalDate.now(ZoneId.of("UTC"));
+        if (requestDate.isAfter(currentDate)) {
+            throw new IllegalArgumentException("Date cannot be in the future");
+        }
+
         ZonedDateTime zonedDateTime = requestDTO.getDate().atStartOfDay(ZoneId.of("UTC"));
         Timestamp timestamp = Timestamp.from(zonedDateTime.toInstant());
 
@@ -96,50 +108,51 @@ public List<Map<String, Integer>> calculateDDay(Anniversary anniversary) {
         LocalDate today = LocalDate.now();
         LocalDateTime anniversaryDateTime = anniversary.getAnniversaryDate().toLocalDateTime();
         LocalDate anniversaryDate = anniversaryDateTime.toLocalDate();
-        long yearsDifference = ChronoUnit.YEARS.between(anniversaryDate, today);
+
+        Map<String, Integer> closestDDay = null;
+        int minDays = Integer.MAX_VALUE;
 
         if (anniversary.getType() == AnniversaryType.연인) {
             int daysPassed = (int) ChronoUnit.DAYS.between(anniversaryDate, today);
             int nextDay = ((daysPassed / 100) + 1) * 100;
 
-            for (int i = 0; i < 2; i++) {
+            for (int i = 0; i < 1; i++) {  // Only find the next closest 100-day anniversary
                 LocalDate hundredDays = anniversaryDate.plusDays(nextDay + i * 100);
                 if (!hundredDays.isBefore(today)) {
-                    Map<String, Integer> dDay = new HashMap<>();
-                    dDay.put((nextDay + i * 100) + "days", (int) ChronoUnit.DAYS.between(today, hundredDays) - 1);
-                    dDayList.add(dDay);
+                    int daysToHundredDays = (int) ChronoUnit.DAYS.between(today, hundredDays) - 1;
+                    if (daysToHundredDays < minDays) {
+                        minDays = daysToHundredDays;
+                        closestDDay = new HashMap<>();
+                        closestDDay.put((nextDay + i * 100) + "days", daysToHundredDays);
+                    }
+                    break;
                 }
             }
         }
 
-        boolean isTodayAnniversary = false;
+        long yearsDifference = ChronoUnit.YEARS.between(anniversaryDate, today);
         for (int i = 1; i <= yearsDifference + 1; i++) {
             LocalDate yearAnniversary = anniversaryDate.plusYears(i);
-            int daysBetween = (int) ChronoUnit.DAYS.between(today, yearAnniversary);
-            if (daysBetween == 0) {
-                Map<String, Integer> dDay = new HashMap<>();
-                dDay.put("year", daysBetween);
-                dDayList.add(dDay);
-                isTodayAnniversary = true;
+            if (!yearAnniversary.isBefore(today)) {
+                int daysToYearAnniversary = (int) ChronoUnit.DAYS.between(today, yearAnniversary);
+                if (daysToYearAnniversary < minDays) {
+                    minDays = daysToYearAnniversary;
+                    closestDDay = new HashMap<>();
+                    closestDDay.put("year", daysToYearAnniversary);
+                }
                 break;
             }
         }
 
-        if (!isTodayAnniversary) {
-            for (int i = 1; i <= yearsDifference + 1; i++) {
-                LocalDate yearAnniversary = anniversaryDate.plusYears(i);
-                if (!yearAnniversary.isBefore(today)) {
-                    Map<String, Integer> dDay = new HashMap<>();
-                    dDay.put("year", (int) ChronoUnit.DAYS.between(today, yearAnniversary));
-                    dDayList.add(dDay);
-                    break;
-                }
-            }
+        if (closestDDay != null) {
+            dDayList.add(closestDDay);
         }
 
+
         return dDayList;
     }
 
+
     public List<AnniversaryResponseDTO> getDDayZeroAnniversaries(List<Anniversary> anniversaries) {
         List<AnniversaryResponseDTO> dDayZeroList = new ArrayList<>();
 
diff --git a/src/main/java/com/example/fiurinee/domain/member/dto/MemberResponseDTO.java b/src/main/java/com/example/fiurinee/domain/member/dto/MemberResponseDTO.java
index ca47770..cacd8ce 100644
--- a/src/main/java/com/example/fiurinee/domain/member/dto/MemberResponseDTO.java
+++ b/src/main/java/com/example/fiurinee/domain/member/dto/MemberResponseDTO.java
@@ -32,13 +32,21 @@ public static MemberResponseDTO of(Member member) {
                 .profileImage(member.getProfileImage())
                 .alarm(member.isAlarm())
                 .anniversaries(member.getAnniversaries().stream()
-                        .map(anniversary -> Map.<String, Object>of(
-                                "id", anniversary.getId(),
-                                "name", anniversary.getName(),
-                                "anniversaryDate", anniversary.getAnniversaryDate().toString().substring(0,10),
-                                "type", anniversary.getType().name(),
-                                "dDays", anniversaryService.calculateDDay(anniversary)
-                        ))
+                        .map(anniversary -> {
+                            List<Map<String, Integer>> dDays = anniversaryService.calculateDDay(anniversary);
+                            return Map.of(
+                                    "id", anniversary.getId(),
+                                    "name", anniversary.getName(),
+                                    "anniversaryDate", anniversary.getAnniversaryDate().toString().substring(0, 10),
+                                    "type", anniversary.getType().name(),
+                                    "dDays", dDays
+                            );
+                        })
+                        .sorted((a1, a2) -> {
+                            Integer dDay1 = (Integer) ((Map<String, Integer>) ((List<?>) a1.get("dDays")).get(0)).values().iterator().next();
+                            Integer dDay2 = (Integer) ((Map<String, Integer>) ((List<?>) a2.get("dDays")).get(0)).values().iterator().next();
+                            return dDay1.compareTo(dDay2);
+                        })
                         .collect(Collectors.toList()))
                 .build();
     }