diff --git a/src/alokasi-topik/alokasi-topik.controller.ts b/src/alokasi-topik/alokasi-topik.controller.ts
index ed647d0f14d1c8ffcdacebd76d455fc2e3c3e1dd..8c095da4d27d04e961dce48cc605c5df62bd0f8d 100644
--- a/src/alokasi-topik/alokasi-topik.controller.ts
+++ b/src/alokasi-topik/alokasi-topik.controller.ts
@@ -59,7 +59,7 @@ export class AlokasiTopikController {
   @Roles(RoleEnum.S2_TIM_TESIS, RoleEnum.ADMIN)
   @Get("/:id")
   async getById(@Param() params: TopikParamDto) {
-    const res = await this.alokasiTopikService.findById(params.id);
+    const res = await this.alokasiTopikService.findActiveTopikById(params.id);
     if (!res) throw new NotFoundException();
     return res as OmittedTopik;
   }
@@ -71,10 +71,12 @@ export class AlokasiTopikController {
     @Query()
     query: TopikQueryDto,
   ) {
-    return await this.alokasiTopikService.findAllCreatedByPembimbing({
-      page: query.page || 1,
-      ...query,
-    });
+    return await this.alokasiTopikService.findAllActiveTopikCreatedByPembimbing(
+      {
+        page: query.page || 1,
+        ...query,
+      },
+    );
   }
 
   @Roles(RoleEnum.S2_TIM_TESIS, RoleEnum.ADMIN)
diff --git a/src/alokasi-topik/alokasi-topik.service.ts b/src/alokasi-topik/alokasi-topik.service.ts
index 3ead15a888e2bde1325675493e7e3620ed188c1c..6a272d71cd1632ada903a4fcddae1a010af2e1b6 100644
--- a/src/alokasi-topik/alokasi-topik.service.ts
+++ b/src/alokasi-topik/alokasi-topik.service.ts
@@ -30,7 +30,7 @@ export class AlokasiTopikService {
     return { ids: ids.map(({ id }) => id) };
   }
 
-  async findById(id: string) {
+  async findActiveTopikById(id: string) {
     return await this.topikRepo.findOne({
       select: {
         id: true,
@@ -45,6 +45,7 @@ export class AlokasiTopikService {
       },
       where: {
         id,
+        aktif: true,
       },
       relations: {
         pengaju: true,
@@ -52,7 +53,7 @@ export class AlokasiTopikService {
     });
   }
 
-  async findAllCreatedByPembimbing(options: {
+  async findAllActiveTopikCreatedByPembimbing(options: {
     page: number;
     limit?: number;
     search?: string;
@@ -71,6 +72,7 @@ export class AlokasiTopikService {
         },
       },
       where: {
+        aktif: true,
         pengaju: {
           id: options.idPembimbing || undefined,
           roles: ArrayContains([RoleEnum.S2_PEMBIMBING]),
@@ -130,10 +132,10 @@ export class AlokasiTopikService {
   }
 
   async update(id: string, updateDto: UpdateTopikDto) {
-    return await this.topikRepo.update(id, updateDto);
+    return await this.topikRepo.update({ id, aktif: true }, updateDto);
   }
 
   async remove(id: string) {
-    return await this.topikRepo.delete({ id }); // TODO: cascade?
+    return await this.topikRepo.update({ id }, { aktif: false });
   }
 }
diff --git a/src/entities/topik.entity.ts b/src/entities/topik.entity.ts
index c3b79e49c17523408d6c619206924fe23a3116e0..e239df1bfc04a3d38be310e45857b1a28ec0c842 100644
--- a/src/entities/topik.entity.ts
+++ b/src/entities/topik.entity.ts
@@ -6,7 +6,7 @@ import {
   PrimaryGeneratedColumn,
 } from "typeorm";
 import { Pengguna } from "./pengguna.entity";
-import { ApiProperty } from "@nestjs/swagger";
+import { ApiHideProperty, ApiProperty } from "@nestjs/swagger";
 
 @Entity()
 export class Topik {
@@ -30,4 +30,8 @@ export class Topik {
   @ApiProperty({ example: "550e8400-e29b-41d4-a716-446655440000" })
   @Column({ nullable: true })
   idPengaju: string;
+
+  @ApiHideProperty()
+  @Column({ type: "boolean", default: true })
+  aktif: boolean;
 }
diff --git a/src/registrasi-tesis/registrasi-tesis.service.ts b/src/registrasi-tesis/registrasi-tesis.service.ts
index c2f221a3092661d1fc9e9c491863b181e9d62c6f..496af6f847fc6bf8451d83810cfbae67233c281e 100644
--- a/src/registrasi-tesis/registrasi-tesis.service.ts
+++ b/src/registrasi-tesis/registrasi-tesis.service.ts
@@ -79,8 +79,14 @@ export class RegistrasiTesisService {
       throw new NotFoundException("Penerima not found.");
     }
 
-    if (topicRegistrationDto.idTopik && !topik) {
-      throw new NotFoundException("Topic not found.");
+    if (topicRegistrationDto.idTopik) {
+      if (!topik) {
+        throw new NotFoundException("Topic not found.");
+      }
+
+      if (!topik.aktif) {
+        throw new BadRequestException("Topic is not active.");
+      }
     }
 
     if (lastPendaftaran && lastPendaftaran.status !== RegStatus.REJECTED) {