diff --git a/apps/server/src/entities/attendance-record.entity.ts b/apps/server/src/entities/attendance-record.entity.ts
index e5a64bd..730df52 100644
--- a/apps/server/src/entities/attendance-record.entity.ts
+++ b/apps/server/src/entities/attendance-record.entity.ts
@@ -10,6 +10,7 @@ import {
 } from 'typeorm';
 import { Student } from './student.entity';
 import { Class } from './class.entity';
+import { Department } from './department.entity';
 
 @Entity('attendance_records')
 @Index(['classId', 'attendanceDate'])
@@ -52,4 +53,11 @@ export class AttendanceRecord {
 
   @UpdateDateColumn({ name: 'updated_at' })
   updatedAt: Date;
+
+  @Column({ name: 'department_id', type: 'integer', nullable: true })
+  departmentId: number;
+
+  @ManyToOne(() => Department, { nullable: true })
+  @JoinColumn({ name: 'department_id' })
+  department: Department;
 }
diff --git a/apps/server/src/entities/bill.entity.ts b/apps/server/src/entities/bill.entity.ts
index dea94e3..50f618b 100644
--- a/apps/server/src/entities/bill.entity.ts
+++ b/apps/server/src/entities/bill.entity.ts
@@ -9,6 +9,7 @@ import {
 } from 'typeorm';
 import { Student } from './student.entity';
 import { BillItem } from './bill-item.entity';
+import { Department } from './department.entity';
 
 @Entity('bills')
 export class Bill {
@@ -45,4 +46,11 @@ export class Bill {
 
   @OneToMany(() => BillItem, (bi) => bi.bill)
   items: BillItem[];
+
+  @Column({ name: 'department_id', type: 'integer', nullable: true })
+  departmentId: number;
+
+  @ManyToOne(() => Department, { nullable: true })
+  @JoinColumn({ name: 'department_id' })
+  department: Department;
 }
diff --git a/apps/server/src/entities/class-schedule.entity.ts b/apps/server/src/entities/class-schedule.entity.ts
index 36e7417..6345781 100644
--- a/apps/server/src/entities/class-schedule.entity.ts
+++ b/apps/server/src/entities/class-schedule.entity.ts
@@ -8,6 +8,7 @@ import {
   JoinColumn,
   Check,
 } from 'typeorm';
+import { Department } from './department.entity';
 
 export enum ScheduleType {
   INTERNAL = 'INTERNAL',
@@ -79,4 +80,11 @@ export class ClassSchedule {
 
   @UpdateDateColumn({ name: 'updated_at' })
   updatedAt: Date;
+
+  @Column({ name: 'department_id', type: 'integer', nullable: true })
+  departmentId: number;
+
+  @ManyToOne(() => Department, { nullable: true })
+  @JoinColumn({ name: 'department_id' })
+  department: Department;
 }
diff --git a/apps/server/src/entities/classroom-rental.entity.ts b/apps/server/src/entities/classroom-rental.entity.ts
index 2127062..03504da 100644
--- a/apps/server/src/entities/classroom-rental.entity.ts
+++ b/apps/server/src/entities/classroom-rental.entity.ts
@@ -10,6 +10,7 @@ import {
 } from 'typeorm';
 import { Classroom } from './classroom.entity';
 import { Tenant } from './tenant.entity';
+import { Department } from './department.entity';
 
 @Entity('classroom_rentals')
 @Index(['classroomId', 'startDate', 'endDate'])
@@ -64,4 +65,11 @@ export class ClassroomRental {
 
   @UpdateDateColumn({ name: 'updated_at' })
   updatedAt: Date;
+
+  @Column({ name: 'department_id', type: 'integer', nullable: true })
+  departmentId: number;
+
+  @ManyToOne(() => Department, { nullable: true })
+  @JoinColumn({ name: 'department_id' })
+  department: Department;
 }
diff --git a/apps/server/src/entities/classroom.entity.ts b/apps/server/src/entities/classroom.entity.ts
index 8aa7021..dc60165 100644
--- a/apps/server/src/entities/classroom.entity.ts
+++ b/apps/server/src/entities/classroom.entity.ts
@@ -1,4 +1,5 @@
-import { Entity, PrimaryGeneratedColumn, Column, CreateDateColumn } from 'typeorm';
+import { Entity, PrimaryGeneratedColumn, Column, CreateDateColumn, ManyToOne, JoinColumn } from 'typeorm';
+import { Department } from './department.entity';
 
 @Entity('classrooms')
 export class Classroom {
@@ -34,4 +35,11 @@ export class Classroom {
 
   @CreateDateColumn({ name: 'created_at' })
   createdAt: Date;
+
+  @Column({ name: 'department_id', type: 'integer', nullable: true })
+  departmentId: number;
+
+  @ManyToOne(() => Department, { nullable: true })
+  @JoinColumn({ name: 'department_id' })
+  department: Department;
 }
diff --git a/apps/server/src/entities/deposit-installment.entity.ts b/apps/server/src/entities/deposit-installment.entity.ts
index 20bd67a..afffc1e 100644
--- a/apps/server/src/entities/deposit-installment.entity.ts
+++ b/apps/server/src/entities/deposit-installment.entity.ts
@@ -7,6 +7,7 @@ import {
   JoinColumn,
 } from 'typeorm';
 import { Deposit } from './deposit.entity';
+import { Department } from './department.entity';
 
 @Entity('deposit_installments')
 export class DepositInstallment {
@@ -34,4 +35,11 @@ export class DepositInstallment {
   @ManyToOne(() => Deposit, (d) => d.installments, { onDelete: 'CASCADE' })
   @JoinColumn({ name: 'deposit_id' })
   deposit: Deposit;
+
+  @Column({ name: 'department_id', type: 'integer', nullable: true })
+  departmentId: number;
+
+  @ManyToOne(() => Department, { nullable: true })
+  @JoinColumn({ name: 'department_id' })
+  department: Department;
 }
diff --git a/apps/server/src/entities/deposit.entity.ts b/apps/server/src/entities/deposit.entity.ts
index b73ef49..d8b3c46 100644
--- a/apps/server/src/entities/deposit.entity.ts
+++ b/apps/server/src/entities/deposit.entity.ts
@@ -9,6 +9,7 @@ import {
 } from 'typeorm';
 import { Student } from './student.entity';
 import { DepositInstallment } from './deposit-installment.entity';
+import { Department } from './department.entity';
 
 @Entity('deposits')
 export class Deposit {
@@ -68,4 +69,10 @@ export class Deposit {
   @JoinColumn({ name: 'student_id' })
   student: Student;
 
+  @Column({ name: 'department_id', type: 'integer', nullable: true })
+  departmentId: number;
+
+  @ManyToOne(() => Department, { nullable: true })
+  @JoinColumn({ name: 'department_id' })
+  department: Department;
 }
diff --git a/apps/server/src/entities/expense-type.entity.ts b/apps/server/src/entities/expense-type.entity.ts
new file mode 100644
index 0000000..1c4785c
--- /dev/null
+++ b/apps/server/src/entities/expense-type.entity.ts
@@ -0,0 +1,25 @@
+import { Entity, PrimaryGeneratedColumn, Column, CreateDateColumn } from 'typeorm';
+
+@Entity('expense_types')
+export class ExpenseType {
+  @PrimaryGeneratedColumn()
+  id: number;
+
+  @Column({ length: 30, unique: true })
+  code: string;
+
+  @Column({ length: 30 })
+  name: string;
+
+  @Column({ length: 20, default: 'room' })
+  category: string;
+
+  @Column({ type: 'integer', default: 0 })
+  sortOrder: number;
+
+  @Column({ default: true })
+  enabled: boolean;
+
+  @CreateDateColumn({ name: 'created_at' })
+  createdAt: Date;
+}
diff --git a/apps/server/src/entities/occupancy.entity.ts b/apps/server/src/entities/occupancy.entity.ts
index 1ead54b..dbabe41 100644
--- a/apps/server/src/entities/occupancy.entity.ts
+++ b/apps/server/src/entities/occupancy.entity.ts
@@ -9,6 +9,7 @@ import {
 import { Student } from './student.entity';
 import { Room } from './room.entity';
 import { Tenant } from './tenant.entity';
+import { Department } from './department.entity';
 
 @Entity('occupancies')
 export class Occupancy {
@@ -59,4 +60,11 @@ export class Occupancy {
   @ManyToOne(() => Room, (r) => r.occupancies)
   @JoinColumn({ name: 'room_id' })
   room: Room;
+
+  @Column({ name: 'department_id', type: 'integer', nullable: true })
+  departmentId: number;
+
+  @ManyToOne(() => Department, { nullable: true })
+  @JoinColumn({ name: 'department_id' })
+  department: Department;
 }
diff --git a/apps/server/src/entities/personal-expense.entity.ts b/apps/server/src/entities/personal-expense.entity.ts
index e0b7c8e..d4d75e5 100644
--- a/apps/server/src/entities/personal-expense.entity.ts
+++ b/apps/server/src/entities/personal-expense.entity.ts
@@ -7,6 +7,7 @@ import {
   JoinColumn,
 } from 'typeorm';
 import { Student } from './student.entity';
+import { Department } from './department.entity';
 
 @Entity('personal_expenses')
 export class PersonalExpense {
@@ -40,4 +41,11 @@ export class PersonalExpense {
   @ManyToOne(() => Student, (s) => s.personalExpenses)
   @JoinColumn({ name: 'student_id' })
   student: Student;
+
+  @Column({ name: 'department_id', type: 'integer', nullable: true })
+  departmentId: number;
+
+  @ManyToOne(() => Department, { nullable: true })
+  @JoinColumn({ name: 'department_id' })
+  department: Department;
 }
diff --git a/apps/server/src/entities/room-expense.entity.ts b/apps/server/src/entities/room-expense.entity.ts
index 1221ccd..74d777c 100644
--- a/apps/server/src/entities/room-expense.entity.ts
+++ b/apps/server/src/entities/room-expense.entity.ts
@@ -7,6 +7,7 @@ import {
   JoinColumn,
 } from 'typeorm';
 import { Room } from './room.entity';
+import { Department } from './department.entity';
 
 @Entity('room_expenses')
 export class RoomExpense {
@@ -40,4 +41,11 @@ export class RoomExpense {
   @ManyToOne(() => Room, (r) => r.roomExpenses)
   @JoinColumn({ name: 'room_id' })
   room: Room;
+
+  @Column({ name: 'department_id', type: 'integer', nullable: true })
+  departmentId: number;
+
+  @ManyToOne(() => Department, { nullable: true })
+  @JoinColumn({ name: 'department_id' })
+  department: Department;
 }
diff --git a/apps/server/src/entities/room.entity.ts b/apps/server/src/entities/room.entity.ts
index 8ab05c6..ddd86ab 100644
--- a/apps/server/src/entities/room.entity.ts
+++ b/apps/server/src/entities/room.entity.ts
@@ -1,6 +1,7 @@
-import { Entity, PrimaryGeneratedColumn, Column, CreateDateColumn, OneToMany } from 'typeorm';
+import { Entity, PrimaryGeneratedColumn, Column, CreateDateColumn, OneToMany, ManyToOne, JoinColumn } from 'typeorm';
 import { Occupancy } from './occupancy.entity';
 import { RoomExpense } from './room-expense.entity';
+import { Department } from './department.entity';
 
 @Entity('rooms')
 export class Room {
@@ -42,4 +43,11 @@ export class Room {
 
   @OneToMany(() => RoomExpense, (e) => e.room)
   roomExpenses: RoomExpense[];
+
+  @Column({ name: 'department_id', type: 'integer', nullable: true })
+  departmentId: number;
+
+  @ManyToOne(() => Department, { nullable: true })
+  @JoinColumn({ name: 'department_id' })
+  department: Department;
 }
diff --git a/apps/server/src/entities/student.entity.ts b/apps/server/src/entities/student.entity.ts
index 1441711..914896e 100644
--- a/apps/server/src/entities/student.entity.ts
+++ b/apps/server/src/entities/student.entity.ts
@@ -14,6 +14,7 @@ import { PersonalExpense } from './personal-expense.entity';
 import { Bill } from './bill.entity';
 import { Tenant } from './tenant.entity';
 import { User } from './user.entity';
+import { Department } from './department.entity';
 
 @Entity('students')
 export class Student {
@@ -80,4 +81,11 @@ export class Student {
 
   @OneToMany(() => Bill, (b) => b.student)
   bills: Bill[];
+
+  @Column({ name: 'department_id', type: 'integer', nullable: true })
+  departmentId: number;
+
+  @ManyToOne(() => Department, { nullable: true })
+  @JoinColumn({ name: 'department_id' })
+  department: Department;
 }