diff --git a/src/main/java/com/faf223/expensetrackerfaf/dto/mappers/ExpenseMapper.java b/src/main/java/com/faf223/expensetrackerfaf/dto/mappers/ExpenseMapper.java
index 74eeff7..466144f 100644
--- a/src/main/java/com/faf223/expensetrackerfaf/dto/mappers/ExpenseMapper.java
+++ b/src/main/java/com/faf223/expensetrackerfaf/dto/mappers/ExpenseMapper.java
@@ -20,7 +20,7 @@ public class ExpenseMapper {
     }
 
     public ExpenseDTO toDto(Expense expense) {
-        return new ExpenseDTO(expense.getExpenseId(), userMapper.toDto(expense.getUser()),
+        return new ExpenseDTO(expense.getId(), userMapper.toDto(expense.getUser()),
                 expense.getCategory(), expense.getDate(), expense.getAmount());
     }
 
diff --git a/src/main/java/com/faf223/expensetrackerfaf/dto/mappers/IncomeMapper.java b/src/main/java/com/faf223/expensetrackerfaf/dto/mappers/IncomeMapper.java
index 32ca33e..5bdd805 100644
--- a/src/main/java/com/faf223/expensetrackerfaf/dto/mappers/IncomeMapper.java
+++ b/src/main/java/com/faf223/expensetrackerfaf/dto/mappers/IncomeMapper.java
@@ -2,7 +2,6 @@ package com.faf223.expensetrackerfaf.dto.mappers;
 
 import com.faf223.expensetrackerfaf.dto.IncomeCreationDTO;
 import com.faf223.expensetrackerfaf.dto.IncomeDTO;
-import com.faf223.expensetrackerfaf.model.Expense;
 import com.faf223.expensetrackerfaf.model.Income;
 import com.faf223.expensetrackerfaf.service.IncomeService;
 import org.springframework.beans.factory.annotation.Autowired;
@@ -21,7 +20,7 @@ public class IncomeMapper {
     }
 
     public IncomeDTO toDto(Income income) {
-        return new IncomeDTO(income.getIncomeId(), userMapper.toDto(income.getUser()),
+        return new IncomeDTO(income.getId(), userMapper.toDto(income.getUser()),
                 income.getCategory(), income.getDate(), income.getAmount());
     }
 
diff --git a/src/main/java/com/faf223/expensetrackerfaf/model/Credential.java b/src/main/java/com/faf223/expensetrackerfaf/model/Credential.java
index f993e9f..ae93f5f 100644
--- a/src/main/java/com/faf223/expensetrackerfaf/model/Credential.java
+++ b/src/main/java/com/faf223/expensetrackerfaf/model/Credential.java
@@ -1,35 +1,35 @@
-    package com.faf223.expensetrackerfaf.model;
+package com.faf223.expensetrackerfaf.model;
 
-    import jakarta.persistence.*;
-    import lombok.AllArgsConstructor;
-    import lombok.Data;
-    import lombok.NoArgsConstructor;
+import jakarta.persistence.*;
+import lombok.AllArgsConstructor;
+import lombok.Data;
+import lombok.NoArgsConstructor;
 
-    @Data
-    @Entity(name = "credentials")
-    @NoArgsConstructor
-    @AllArgsConstructor
-    public class Credential {
-        @Id
-        @GeneratedValue(strategy = GenerationType.IDENTITY)
-        private Long credentialId;
+@Data
+@Entity(name = "credentials")
+@NoArgsConstructor
+@AllArgsConstructor
+public class Credential {
+    @Id
+    @GeneratedValue(strategy = GenerationType.IDENTITY)
+    private Long credentialId;
 
-        @ManyToOne
-        @JoinColumn(name = "user_uuid")
-        private User user;
+    @ManyToOne
+    @JoinColumn(name = "user_uuid")
+    private User user;
 
-        private String email;
-        private String password;
+    private String email;
+    private String password;
 
-        @Enumerated(EnumType.STRING)
-        private Role role;
+    @Enumerated(EnumType.STRING)
+    private Role role;
 
-        public Credential(User user, String email, String password) {
-            this.user = user;
-            this.email = email;
-            this.password = password;
+    public Credential(User user, String email, String password) {
+        this.user = user;
+        this.email = email;
+        this.password = password;
 
-            this.role = Role.ROLE_USER;
-        }
+        this.role = Role.ROLE_USER;
     }
+}
 
diff --git a/src/main/java/com/faf223/expensetrackerfaf/model/Expense.java b/src/main/java/com/faf223/expensetrackerfaf/model/Expense.java
index 6bdccb1..32fe40d 100644
--- a/src/main/java/com/faf223/expensetrackerfaf/model/Expense.java
+++ b/src/main/java/com/faf223/expensetrackerfaf/model/Expense.java
@@ -1,10 +1,7 @@
 package com.faf223.expensetrackerfaf.model;
 import com.fasterxml.jackson.annotation.JsonIgnore;
 import jakarta.persistence.*;
-import lombok.AllArgsConstructor;
-import lombok.Data;
-import lombok.ToString;
-import lombok.NoArgsConstructor;
+import lombok.*;
 
 import java.math.BigDecimal;
 import java.time.LocalDate;
@@ -13,10 +10,11 @@ import java.time.LocalDate;
 @AllArgsConstructor
 @NoArgsConstructor
 @Entity(name = "expenses")
-public class Expense {
+public class Expense implements IMoneyTransaction {
     @Id
     @GeneratedValue(strategy = GenerationType.IDENTITY)
-    private Long expenseId;
+    @Column(name = "expense_id")
+    private Long id;
 
     @ManyToOne()
     @JoinColumn(name = "user_uuid")
diff --git a/src/main/java/com/faf223/expensetrackerfaf/model/ExpenseCategory.java b/src/main/java/com/faf223/expensetrackerfaf/model/ExpenseCategory.java
index 7662ce6..c5989ea 100644
--- a/src/main/java/com/faf223/expensetrackerfaf/model/ExpenseCategory.java
+++ b/src/main/java/com/faf223/expensetrackerfaf/model/ExpenseCategory.java
@@ -1,17 +1,16 @@
 package com.faf223.expensetrackerfaf.model;
 
-import jakarta.persistence.Entity;
-import jakarta.persistence.GeneratedValue;
-import jakarta.persistence.GenerationType;
-import jakarta.persistence.Id;
+import jakarta.persistence.*;
 import lombok.Data;
 
 @Data
 @Entity(name = "expense_categories")
-public class ExpenseCategory {
+public class ExpenseCategory implements IMoneyTransactionCategory {
     @Id
     @GeneratedValue(strategy = GenerationType.IDENTITY)
-    private Long categoryId;
+    @Column(name = "category_id")
+    private Long id;
 
-    private String categoryName;
+    @Column(name = "category_name")
+    private String name;
 }
diff --git a/src/main/java/com/faf223/expensetrackerfaf/model/IMoneyTransaction.java b/src/main/java/com/faf223/expensetrackerfaf/model/IMoneyTransaction.java
new file mode 100644
index 0000000..f565db3
--- /dev/null
+++ b/src/main/java/com/faf223/expensetrackerfaf/model/IMoneyTransaction.java
@@ -0,0 +1,14 @@
+package com.faf223.expensetrackerfaf.model;
+
+import java.math.BigDecimal;
+import java.time.LocalDate;
+
+public interface IMoneyTransaction {
+
+    Long getId();
+    LocalDate getDate();
+    User getUser();
+    BigDecimal getAmount();
+    IMoneyTransactionCategory getCategory();
+
+}
diff --git a/src/main/java/com/faf223/expensetrackerfaf/model/IMoneyTransactionCategory.java b/src/main/java/com/faf223/expensetrackerfaf/model/IMoneyTransactionCategory.java
new file mode 100644
index 0000000..f326a9b
--- /dev/null
+++ b/src/main/java/com/faf223/expensetrackerfaf/model/IMoneyTransactionCategory.java
@@ -0,0 +1,6 @@
+package com.faf223.expensetrackerfaf.model;
+
+public interface IMoneyTransactionCategory {
+    Long getId();
+    String getName();
+}
diff --git a/src/main/java/com/faf223/expensetrackerfaf/model/Income.java b/src/main/java/com/faf223/expensetrackerfaf/model/Income.java
index a4c88f1..967fa3b 100644
--- a/src/main/java/com/faf223/expensetrackerfaf/model/Income.java
+++ b/src/main/java/com/faf223/expensetrackerfaf/model/Income.java
@@ -2,10 +2,8 @@ package com.faf223.expensetrackerfaf.model;
 
 import com.fasterxml.jackson.annotation.JsonIgnore;
 import jakarta.persistence.*;
-import lombok.AllArgsConstructor;
-import lombok.Data;
-import lombok.ToString;
-import lombok.NoArgsConstructor;
+import lombok.*;
+
 import java.math.BigDecimal;
 import java.time.LocalDate;
 
@@ -13,10 +11,11 @@ import java.time.LocalDate;
 @AllArgsConstructor
 @NoArgsConstructor
 @Entity(name = "incomes")
-public class Income {
+public class Income implements IMoneyTransaction {
     @Id
     @GeneratedValue(strategy = GenerationType.IDENTITY)
-    private Long incomeId;
+    @Column(name = "income_id")
+    private Long id;
 
     @ManyToOne
     @JoinColumn(name = "user_uuid")
diff --git a/src/main/java/com/faf223/expensetrackerfaf/model/IncomeCategory.java b/src/main/java/com/faf223/expensetrackerfaf/model/IncomeCategory.java
index 8bb54f0..237c41f 100644
--- a/src/main/java/com/faf223/expensetrackerfaf/model/IncomeCategory.java
+++ b/src/main/java/com/faf223/expensetrackerfaf/model/IncomeCategory.java
@@ -1,18 +1,17 @@
 package com.faf223.expensetrackerfaf.model;
 
-import jakarta.persistence.Entity;
-import jakarta.persistence.GeneratedValue;
-import jakarta.persistence.GenerationType;
-import jakarta.persistence.Id;
+import jakarta.persistence.*;
 import lombok.Data;
 
 @Data
 @Entity(name = "income_categories")
-public class IncomeCategory {
+public class IncomeCategory implements IMoneyTransactionCategory {
     @Id
     @GeneratedValue(strategy = GenerationType.IDENTITY)
-    private Long categoryId;
+    @Column(name = "category_id")
+    private Long id;
 
-    private String categoryName;
+    @Column(name = "category_name")
+    private String name;
 }
 
diff --git a/src/main/java/com/faf223/expensetrackerfaf/model/Role.java b/src/main/java/com/faf223/expensetrackerfaf/model/Role.java
index ea04328..6169bd2 100644
--- a/src/main/java/com/faf223/expensetrackerfaf/model/Role.java
+++ b/src/main/java/com/faf223/expensetrackerfaf/model/Role.java
@@ -1,4 +1,3 @@
-
 package com.faf223.expensetrackerfaf.model;
 
 public enum Role {
diff --git a/src/main/java/com/faf223/expensetrackerfaf/model/User.java b/src/main/java/com/faf223/expensetrackerfaf/model/User.java
index 339416f..9588570 100644
--- a/src/main/java/com/faf223/expensetrackerfaf/model/User.java
+++ b/src/main/java/com/faf223/expensetrackerfaf/model/User.java
@@ -1,4 +1,3 @@
-
 package com.faf223.expensetrackerfaf.model;
 
 import jakarta.persistence.*;
diff --git a/src/main/java/com/faf223/expensetrackerfaf/util/IMoneyTransaction.java b/src/main/java/com/faf223/expensetrackerfaf/util/IMoneyTransaction.java
deleted file mode 100644
index 8817420..0000000
--- a/src/main/java/com/faf223/expensetrackerfaf/util/IMoneyTransaction.java
+++ /dev/null
@@ -1,11 +0,0 @@
-package com.faf223.expensetrackerfaf.util;
-
-import com.faf223.expensetrackerfaf.model.User;
-
-public interface IMoneyTransaction {
-
-    User getUser();
-    int getAmount();
-    String getCategory();
-
-}