diff --git a/src/main/java/com/faf223/expensetrackerfaf/config/ApplicationConfig.java b/src/main/java/com/faf223/expensetrackerfaf/config/ApplicationConfig.java
index 57d1823..fd41b70 100644
--- a/src/main/java/com/faf223/expensetrackerfaf/config/ApplicationConfig.java
+++ b/src/main/java/com/faf223/expensetrackerfaf/config/ApplicationConfig.java
@@ -1,8 +1,7 @@
 package com.faf223.expensetrackerfaf.config;
 
-import com.faf223.expensetrackerfaf.repository.CredentialRepository;
-import com.faf223.expensetrackerfaf.repository.UserRepository;
 import com.faf223.expensetrackerfaf.security.PersonDetails;
+import com.faf223.expensetrackerfaf.service.CredentialService;
 import lombok.RequiredArgsConstructor;
 import org.springframework.context.annotation.Bean;
 import org.springframework.context.annotation.Configuration;
@@ -19,12 +18,11 @@ import org.springframework.security.crypto.password.PasswordEncoder;
 @RequiredArgsConstructor
 public class ApplicationConfig {
 
-    private final UserRepository userRepository;
-    private final CredentialRepository credentialRepository;
+    private final CredentialService credentialService;
 
     @Bean
     public UserDetailsService userDetailsService() {
-        return username -> new PersonDetails(credentialRepository.findByEmail(username).orElseThrow((() -> new UsernameNotFoundException("User not found"))));
+        return username -> new PersonDetails(credentialService.findByEmail(username).orElseThrow((() -> new UsernameNotFoundException("User not found"))));
     }
 
     @Bean
diff --git a/src/main/java/com/faf223/expensetrackerfaf/controller/ExpenseController.java b/src/main/java/com/faf223/expensetrackerfaf/controller/ExpenseController.java
index ec91ea7..84da712 100644
--- a/src/main/java/com/faf223/expensetrackerfaf/controller/ExpenseController.java
+++ b/src/main/java/com/faf223/expensetrackerfaf/controller/ExpenseController.java
@@ -2,7 +2,6 @@ package com.faf223.expensetrackerfaf.controller;
 
 import com.faf223.expensetrackerfaf.dto.ExpenseCreationDTO;
 import com.faf223.expensetrackerfaf.dto.ExpenseDTO;
-import com.faf223.expensetrackerfaf.dto.IncomeDTO;
 import com.faf223.expensetrackerfaf.dto.mappers.ExpenseMapper;
 import com.faf223.expensetrackerfaf.model.Expense;
 import com.faf223.expensetrackerfaf.model.ExpenseCategory;
@@ -23,6 +22,7 @@ import org.springframework.security.access.prepost.PreAuthorize;
 import org.springframework.security.core.Authentication;
 import org.springframework.security.core.context.SecurityContextHolder;
 import org.springframework.security.core.userdetails.UserDetails;
+import org.springframework.transaction.annotation.Transactional;
 import org.springframework.validation.BindingResult;
 import org.springframework.web.bind.annotation.*;
 
@@ -97,8 +97,9 @@ public class ExpenseController {
     }
 
     @GetMapping("/personal-expenses")
+    @Transactional(readOnly = true)
     public ResponseEntity<List<ExpenseDTO>> getExpensesByUser(@RequestParam Optional<LocalDate> date,
-                                                              @RequestParam Optional<Month> month,
+                                                              @RequestParam Optional<Integer> month,
                                                               @RequestParam Optional<Integer> startYear,
                                                               @RequestParam Optional<Integer> endYear,
                                                               @RequestParam Optional<String> lastUnit) {
@@ -113,7 +114,7 @@ public class ExpenseController {
             if(date.isPresent())
                 expenses = expenseService.getTransactionsByDate(date.get(), email).stream().map(expenseMapper::toDto).toList();
             else if(month.isPresent())
-                expenses = expenseService.getTransactionsByMonth(month.get(), email).stream().map(expenseMapper::toDto).toList();
+                expenses = expenseService.getTransactionsByMonth(Month.of(month.get()), email).stream().map(expenseMapper::toDto).toList();
             else if(startYear.isPresent() && endYear.isPresent())
                 expenses = expenseService.getYearIntervalTransactions(email, startYear.get(), endYear.get()).stream().map(expenseMapper::toDto).toList();
             else if(lastUnit.isPresent()) {
diff --git a/src/main/java/com/faf223/expensetrackerfaf/controller/IncomeController.java b/src/main/java/com/faf223/expensetrackerfaf/controller/IncomeController.java
index 0e2a888..c66a544 100644
--- a/src/main/java/com/faf223/expensetrackerfaf/controller/IncomeController.java
+++ b/src/main/java/com/faf223/expensetrackerfaf/controller/IncomeController.java
@@ -22,6 +22,7 @@ import org.springframework.security.access.prepost.PreAuthorize;
 import org.springframework.security.core.Authentication;
 import org.springframework.security.core.context.SecurityContextHolder;
 import org.springframework.security.core.userdetails.UserDetails;
+import org.springframework.transaction.annotation.Transactional;
 import org.springframework.validation.BindingResult;
 import org.springframework.web.bind.annotation.*;
 
@@ -96,8 +97,9 @@ public class IncomeController {
     }
 
     @GetMapping("/personal-incomes")
-    public ResponseEntity<List<IncomeDTO>> getExpensesByUser(@RequestParam Optional<LocalDate> date,
-                                                             @RequestParam Optional<Month> month,
+    @Transactional(readOnly = true)
+    public ResponseEntity<List<IncomeDTO>> getIncomesByUser(@RequestParam Optional<LocalDate> date,
+                                                             @RequestParam Optional<Integer> month,
                                                              @RequestParam Optional<Integer> startYear,
                                                              @RequestParam Optional<Integer> endYear,
                                                              @RequestParam Optional<String> lastUnit) {
@@ -112,7 +114,7 @@ public class IncomeController {
             if(date.isPresent())
                 incomes = incomeService.getTransactionsByDate(date.get(), email).stream().map(incomeMapper::toDto).toList();
             else if(month.isPresent())
-                incomes = incomeService.getTransactionsByMonth(month.get(), email).stream().map(incomeMapper::toDto).toList();
+                incomes = incomeService.getTransactionsByMonth(Month.of(month.get()), email).stream().map(incomeMapper::toDto).toList();
             else if(startYear.isPresent() && endYear.isPresent())
                 incomes = incomeService.getYearIntervalTransactions(email, startYear.get(), endYear.get()).stream().map(incomeMapper::toDto).toList();
             else if(lastUnit.isPresent()) {
diff --git a/src/main/java/com/faf223/expensetrackerfaf/repository/IncomeRepository.java b/src/main/java/com/faf223/expensetrackerfaf/repository/IncomeRepository.java
index 013131d..d1cd7a2 100644
--- a/src/main/java/com/faf223/expensetrackerfaf/repository/IncomeRepository.java
+++ b/src/main/java/com/faf223/expensetrackerfaf/repository/IncomeRepository.java
@@ -5,6 +5,7 @@ import com.faf223.expensetrackerfaf.model.User;
 import org.springframework.data.jpa.repository.JpaRepository;
 import org.springframework.data.jpa.repository.query.Procedure;
 import org.springframework.stereotype.Repository;
+import org.springframework.transaction.annotation.Transactional;
 
 import java.time.LocalDate;
 import java.util.List;
@@ -16,15 +17,19 @@ public interface IncomeRepository extends JpaRepository<Income, Long> {
 
     List<Income> findByDateBetween(LocalDate start, LocalDate end);
 
+    @Transactional(readOnly = true)
     @Procedure(procedureName = "get_incomes_by_month")
     List<Income> filterByMonth(int month);
 
+    @Transactional(readOnly = true)
     @Procedure(procedureName = "get_last_week_incomes")
     List<Income> findLastWeek();
 
+    @Transactional(readOnly = true)
     @Procedure(procedureName = "get_last_month_incomes")
     List<Income> findLastMonth();
 
+    @Transactional(readOnly = true)
     @Procedure(procedureName = "get_incomes_by_year_interval")
     List<Income> filterByYearInterval(int start, int end);
 }
diff --git a/src/main/java/com/faf223/expensetrackerfaf/service/CredentialService.java b/src/main/java/com/faf223/expensetrackerfaf/service/CredentialService.java
index cd68ab2..180f029 100644
--- a/src/main/java/com/faf223/expensetrackerfaf/service/CredentialService.java
+++ b/src/main/java/com/faf223/expensetrackerfaf/service/CredentialService.java
@@ -5,14 +5,16 @@ import com.faf223.expensetrackerfaf.repository.CredentialRepository;
 import lombok.RequiredArgsConstructor;
 import org.springframework.stereotype.Service;
 
+import java.util.Optional;
+
 @Service
 @RequiredArgsConstructor
 public class CredentialService {
 
     private final CredentialRepository credentialRepository;
 
-    public Credential findByEmail(String email) {
-        return credentialRepository.findByEmail(email).orElse(null);
+    public Optional<Credential> findByEmail(String email) {
+        return credentialRepository.findByEmail(email);
     }
 
 }
diff --git a/src/main/java/com/faf223/expensetrackerfaf/service/ExpenseService.java b/src/main/java/com/faf223/expensetrackerfaf/service/ExpenseService.java
index bc0a690..1ded82e 100644
--- a/src/main/java/com/faf223/expensetrackerfaf/service/ExpenseService.java
+++ b/src/main/java/com/faf223/expensetrackerfaf/service/ExpenseService.java
@@ -12,6 +12,7 @@ import org.springframework.security.core.Authentication;
 import org.springframework.security.core.context.SecurityContextHolder;
 import org.springframework.security.core.userdetails.UserDetails;
 import org.springframework.stereotype.Service;
+import org.springframework.transaction.annotation.Transactional;
 
 import java.time.LocalDate;
 import java.time.Month;
diff --git a/src/main/java/com/faf223/expensetrackerfaf/service/IncomeService.java b/src/main/java/com/faf223/expensetrackerfaf/service/IncomeService.java
index d778ac8..5b56d4b 100644
--- a/src/main/java/com/faf223/expensetrackerfaf/service/IncomeService.java
+++ b/src/main/java/com/faf223/expensetrackerfaf/service/IncomeService.java
@@ -56,15 +56,7 @@ public class IncomeService implements ITransactionService {
 
     @Override
     public List<Income> getTransactionsByDate(LocalDate date, String email) {
-        return getTransactionsByDate(date)
-                .stream()
-                .filter(transaction -> {
-                    Optional<Credential> credential = credentialRepository.findByEmail(email);
-                    if(credential.isEmpty())
-                        throw new UserNotFoundException("The user has not been found");
-                    return credential.get().getUser().equals(transaction.getUser());
-                })
-                .toList();
+        return (List<Income>) transactionFilter.filterByEmail(getTransactionsByDate(date), email);
     }
 
     @Override
@@ -74,15 +66,7 @@ public class IncomeService implements ITransactionService {
 
     @Override
     public List<Income> getTransactionsByMonth(Month month, String email) {
-        return getTransactionsByMonth(month)
-                .stream()
-                .filter(transaction -> {
-                    Optional<Credential> credential = credentialRepository.findByEmail(email);
-                    if(credential.isEmpty())
-                        throw new UserNotFoundException("The user has not been found");
-                    return credential.get().getUser().equals(transaction.getUser());
-                })
-                .toList();
+        return (List<Income>) transactionFilter.filterByEmail(getTransactionsByMonth(month), email);
     }
 
     @Override
diff --git a/src/main/java/com/faf223/expensetrackerfaf/util/TransactionFilter.java b/src/main/java/com/faf223/expensetrackerfaf/util/TransactionFilter.java
index 3f27dd7..f6380b5 100644
--- a/src/main/java/com/faf223/expensetrackerfaf/util/TransactionFilter.java
+++ b/src/main/java/com/faf223/expensetrackerfaf/util/TransactionFilter.java
@@ -8,6 +8,7 @@ import lombok.RequiredArgsConstructor;
 import org.springframework.stereotype.Component;
 
 import java.util.List;
+import java.util.Optional;
 
 @Component
 @RequiredArgsConstructor
@@ -19,10 +20,10 @@ public class TransactionFilter {
         return transactions
                 .stream()
                 .filter(transaction -> {
-                    Credential credential = credentialService.findByEmail(email);
-                    if(credential == null)
+                    Optional<Credential> credential = credentialService.findByEmail(email);
+                    if(credential.isEmpty())
                         throw new UserNotFoundException("The user has not been found");
-                    return credential.getUser().equals(transaction.getUser());
+                    return credential.get().getUser().equals(transaction.getUser());
                 })
                 .toList();
     }