diff --git a/lib/api/apis/aggregated_expense_api.dart b/lib/api/apis/aggregated_expense_api.dart
index ef8d340..15482b5 100644
--- a/lib/api/apis/aggregated_expense_api.dart
+++ b/lib/api/apis/aggregated_expense_api.dart
@@ -10,10 +10,10 @@ class AggregatedExpenseApi {
   Future<int> create(
       {required final double amount,
       required final DateTime monthDate,
-      required final List<String> tags}) async {
+      required final String tags}) async {
     return _db.into(_db.aggregatedExpenseTable).insert(
         AggregatedExpenseTableCompanion.insert(
-            amount: amount, tags: processTag(tags), createdMonthDate: monthDate));
+            amount: amount, tags: tags, createdMonthDate: monthDate));
   }
 
   Future<List<AggregatedExpenseDO>> get() async {
@@ -29,12 +29,10 @@ class AggregatedExpenseApi {
   }
 
   Future<AggregatedExpenseDO?> getByMonthAndTag(
-      {required final DateTime monthDate,
-      required final List<String> tags}) async {
+      {required final DateTime monthDate, required final String tags}) async {
     return (_db.select(_db.aggregatedExpenseTable)
           ..where((t) =>
-              t.createdMonthDate.equals(monthDate) &
-              t.tags.equals(processTag(tags))))
+              t.createdMonthDate.equals(monthDate) & t.tags.equals(tags)))
         .getSingleOrNull();
   }
 
@@ -42,12 +40,12 @@ class AggregatedExpenseApi {
       {required final int id,
       required final double amount,
       required final DateTime createdOn,
-      required final List<String> tags}) async {
+      required final String tags}) async {
     return (_db.update(_db.aggregatedExpenseTable)
           ..where((t) => t.id.equals(id)))
         .write(AggregatedExpenseTableCompanion(
             amount: Value(amount),
-            tags: Value(processTag(tags)),
+            tags: Value(tags),
             createdMonthDate: Value(createdOn)));
   }
 
@@ -62,9 +60,4 @@ class AggregatedExpenseApi {
           ..where((t) => t.createdMonthDate.equals(monthDate)))
         .go();
   }
-
-  String processTag(final List<String> tags) {
-    tags.sort();
-    return tags.join(',');
-  }
 }
diff --git a/lib/api/apis/expense_api.dart b/lib/api/apis/expense_api.dart
index 01103c6..bbda193 100644
--- a/lib/api/apis/expense_api.dart
+++ b/lib/api/apis/expense_api.dart
@@ -10,11 +10,11 @@ class ExpenseApi {
       {required final double amount,
       required final String? description,
       required final DateTime createdOn,
-      required final List<String> tags}) async {
+      required final String tags}) async {
     return _db.into(_db.expenseTable).insert(ExpenseTableCompanion.insert(
         amount: amount,
         description: Value(description),
-        tags: tags.join(','),
+        tags: tags,
         createdOn: createdOn));
   }
 
@@ -44,12 +44,12 @@ class ExpenseApi {
       required final double amount,
       required final String? description,
       required final DateTime createdOn,
-      required final List<String> tags}) async {
+      required final String tags}) async {
     return (_db.update(_db.expenseTable)..where((t) => t.id.equals(id))).write(
         ExpenseTableCompanion(
             amount: Value(amount),
             description: Value(description),
-            tags: Value(tags.join(',')),
+            tags: Value(tags),
             createdOn: Value(createdOn)));
   }
 
@@ -58,7 +58,10 @@ class ExpenseApi {
   }
 
   Future<int> deleteByMonthDate({required final DateTime monthDate}) async {
-    return (_db.delete(_db.expenseTable)..where((t) => t.createdOn.year.equals(monthDate.year) &
-              t.createdOn.month.equals(monthDate.month))).go();
+    return (_db.delete(_db.expenseTable)
+          ..where((t) =>
+              t.createdOn.year.equals(monthDate.year) &
+              t.createdOn.month.equals(monthDate.month)))
+        .go();
   }
 }
diff --git a/lib/domain/services/expense_service.dart b/lib/domain/services/expense_service.dart
index 92952a4..b3b7ca3 100644
--- a/lib/domain/services/expense_service.dart
+++ b/lib/domain/services/expense_service.dart
@@ -1,5 +1,6 @@
 import 'package:wealth_wave/api/apis/aggregated_expense_api.dart';
 import 'package:wealth_wave/api/apis/expense_api.dart';
+import 'package:wealth_wave/api/db/app_database.dart';
 import 'package:wealth_wave/domain/models/aggregated_expense.dart';
 import 'package:wealth_wave/domain/models/expense.dart';
 
@@ -19,127 +20,113 @@ class ExpenseService {
       : _expenseApi = expenseApi ?? ExpenseApi(),
         _aggregatedExpenseApi = aggregatedExpenseApi ?? AggregatedExpenseApi();
 
-  Future<Expense> createExpense({
+  Future<void> createExpense({
     required final String? description,
     required final double amount,
     required final List<String> tags,
     required final DateTime createdOn,
   }) async {
-    final int id = await _expenseApi.create(
+    final tagsString = _processTags(tags: tags);
+    await _updateAggregatedExpense(
+        dateTime: createdOn, tags: tagsString, amount: amount);
+    await _expenseApi.create(
       description: description,
       amount: amount,
-      tags: tags,
+      tags: tagsString,
       createdOn: createdOn,
     );
-    final expenseDO = await _expenseApi.getBy(id: id);
-
-    final DateTime monthDate = DateTime(createdOn.year, createdOn.month);
-    final aggregatedExpense = await _aggregatedExpenseApi.getByMonthAndTag(
-      monthDate: monthDate,
-      tags: tags,
-    );
-
-    if (aggregatedExpense == null) {
-      await _aggregatedExpenseApi.create(
-        amount: amount,
-        monthDate: monthDate,
-        tags: tags,
-      );
-    } else {
-      await _aggregatedExpenseApi.update(
-        id: aggregatedExpense.id,
-        amount: aggregatedExpense.amount + amount,
-        createdOn: monthDate,
-        tags: tags,
-      );
-    }
-
-    return Expense.from(expenseDO: expenseDO);
   }
 
-  Future<Expense> updateExpense({
+  Future<void> updateExpense({
     required final int id,
     required final String? description,
     required final double amount,
     required final List<String> tags,
     required final DateTime createdOn,
   }) async {
-    final expenseDO = await _expenseApi.getBy(id: id);
-    DateTime monthDate =
-        DateTime(expenseDO.createdOn.year, expenseDO.createdOn.month);
-
-    final aggregatedExpense = await _aggregatedExpenseApi.getByMonthAndTag(
-        monthDate: monthDate, tags: tags);
-    if (aggregatedExpense != null) {
-      await _aggregatedExpenseApi.update(
-        id: aggregatedExpense.id,
-        amount: aggregatedExpense.amount -
-            expenseDO.amount +
-            amount, // Adjust the amount correctly
-        createdOn: monthDate,
-        tags: tags,
-      );
-    } else {
-      await _aggregatedExpenseApi.create(
-          amount: amount, monthDate: monthDate, tags: tags);
-    }
-
+    final existingExpenseDO = await _expenseApi.getBy(id: id);
+    await _updateAggregatedExpense(
+        dateTime: existingExpenseDO.createdOn,
+        tags: existingExpenseDO.tags,
+        amount: -existingExpenseDO.amount);
+
+    final tagsString = _processTags(tags: tags);
+    await _updateAggregatedExpense(
+        dateTime: createdOn, tags: tagsString, amount: amount);
     await _expenseApi.update(
-      id: id,
-      description: description,
-      amount: amount,
-      tags: tags,
-      createdOn: createdOn,
-    );
-
-    return await _expenseApi
-        .getBy(id: id)
-        .then((value) => Expense.from(expenseDO: value));
+        id: id,
+        amount: amount,
+        description: description,
+        createdOn: createdOn,
+        tags: tagsString);
   }
 
-  Future<Expense> getById({required final int id}) => _expenseApi
-      .getBy(id: id)
-      .then((expenseDO) => Expense.from(expenseDO: expenseDO));
+  Future<Expense> getById({required final int id}) async {
+    ExpenseDO expenseDO = await _expenseApi.getBy(id: id);
+    return Expense.from(expenseDO: expenseDO);
+  }
 
   Future<List<Expense>> getExpensesForMonthDate(
-      {required final DateTime monthDate}) {
-    return _expenseApi.getByMonth(monthDate: monthDate).then((expenseDOs) =>
-        expenseDOs
-            .map((expenseDO) => Expense.from(expenseDO: expenseDO))
-            .toList());
+      {required final DateTime monthDate}) async {
+    List<ExpenseDO> expenseDOs =
+        await _expenseApi.getByMonth(monthDate: monthDate);
+    return expenseDOs
+        .map((expenseDO) => Expense.from(expenseDO: expenseDO))
+        .toList();
   }
 
   Future<void> deleteBy({required final int id}) async {
-    final expenseDO = await _expenseApi.getBy(id: id);
-    DateTime monthDate =
-        DateTime(expenseDO.createdOn.year, expenseDO.createdOn.month);
-    final aggregatedExpense = await _aggregatedExpenseApi.getByMonthAndTag(
-        monthDate: monthDate, tags: expenseDO.tags.split(','));
-
-    if (aggregatedExpense != null) {
-      await _aggregatedExpenseApi.update(
-          id: aggregatedExpense.id,
-          amount: aggregatedExpense.amount - expenseDO.amount,
-          createdOn: monthDate,
-          tags: expenseDO.tags.split(','));
-    }
-
+    final existingExpenseDO = await _expenseApi.getBy(id: id);
+    await _updateAggregatedExpense(
+        dateTime: existingExpenseDO.createdOn,
+        tags: existingExpenseDO.tags,
+        amount: -existingExpenseDO.amount);
     await _expenseApi.deleteBy(id: id);
   }
 
   Future<void> deleteAggregatedExpense(
       {required final DateTime monthDate}) async {
-    return _expenseApi
-        .deleteByMonthDate(monthDate: monthDate)
-        .then((value) =>
-            _aggregatedExpenseApi.deleteByMonthDate(monthDate: monthDate))
-        .then((value) => null);
+    await _expenseApi.deleteByMonthDate(monthDate: monthDate);
+    await _aggregatedExpenseApi.deleteByMonthDate(monthDate: monthDate);
+  }
+
+  Future<List<AggregatedExpense>> getAggregatedExpenses() async {
+    List<AggregatedExpenseDO> aggregatedExpenseDOs =
+        await _aggregatedExpenseApi.get();
+    return aggregatedExpenseDOs
+        .map((aggregatedExpenseDO) =>
+            AggregatedExpense.from(expenseDO: aggregatedExpenseDO))
+        .toList();
+  }
+
+  Future<void> _updateAggregatedExpense(
+      {required final DateTime dateTime,
+      required final String tags,
+      required final double amount}) async {
+    final monthDate = DateTime(dateTime.year, dateTime.month);
+    final aggregatedExpense = await _aggregatedExpenseApi.getByMonthAndTag(
+      monthDate: monthDate,
+      tags: tags,
+    );
+
+    if (aggregatedExpense == null) {
+      await _aggregatedExpenseApi.create(
+        amount: amount,
+        monthDate: monthDate,
+        tags: tags,
+      );
+    } else {
+      await _aggregatedExpenseApi.update(
+        id: aggregatedExpense.id,
+        amount: aggregatedExpense.amount + amount,
+        createdOn: monthDate,
+        tags: tags,
+      );
+    }
   }
 
-  Future<List<AggregatedExpense>> getAggregatedExpenses() =>
-      _aggregatedExpenseApi.get().then((aggregatedExpenseDOs) =>
-          aggregatedExpenseDOs
-              .map((aggregatedExpenseDO) =>
-                  AggregatedExpense.from(expenseDO: aggregatedExpenseDO))
-              .toList());
+  String _processTags({required final List<String> tags}) {
+    tags.sort();
+    return tags.join(',');
+  }
 }