diff --git a/backend/src/modules/tags/services/tags.service.ts b/backend/src/modules/tags/services/tags.service.ts
index 5cf91e3..243a28c 100644
--- a/backend/src/modules/tags/services/tags.service.ts
+++ b/backend/src/modules/tags/services/tags.service.ts
@@ -1,4 +1,4 @@
-import { Injectable, NotFoundException, Inject } from '@nestjs/common';
+import { Injectable, NotFoundException, Inject, BadRequestException } from '@nestjs/common';
 import { eq, and } from 'drizzle-orm';
 import { DRIZZLE } from '../../../database/database.module';
 import * as schema from '../../../database/schema';
@@ -47,11 +47,11 @@ export class TagsService {
       .select()
       .from(schema.tags)
       .where(eq(schema.tags.id, id));
-    
+
     if (!tag) {
       throw new NotFoundException(`Tag with ID ${id} not found`);
     }
-    
+
     return tag;
   }
 
@@ -67,11 +67,11 @@ export class TagsService {
       })
       .where(eq(schema.tags.id, id))
       .returning();
-    
+
     if (!tag) {
       throw new NotFoundException(`Tag with ID ${id} not found`);
     }
-    
+
     return tag;
   }
 
@@ -83,11 +83,11 @@ export class TagsService {
       .delete(schema.tags)
       .where(eq(schema.tags.id, id))
       .returning();
-    
+
     if (!tag) {
       throw new NotFoundException(`Tag with ID ${id} not found`);
     }
-    
+
     return tag;
   }
 
@@ -95,22 +95,30 @@ export class TagsService {
    * Add a tag to a person
    */
   async addTagToPerson(tagId: string, personId: string) {
+    // Validate tagId and personId
+    if (!tagId) {
+      throw new BadRequestException('Tag ID is required');
+    }
+    if (!personId) {
+      throw new BadRequestException('Person ID is required');
+    }
+
     // Check if the tag exists and is of type PERSON
     const tag = await this.findById(tagId);
     if (tag.type !== 'PERSON') {
-      throw new Error(`Tag with ID ${tagId} is not of type PERSON`);
+      throw new BadRequestException(`Tag with ID ${tagId} is not of type PERSON`);
     }
-    
+
     // Check if the person exists
     const [person] = await this.db
       .select()
       .from(schema.persons)
       .where(eq(schema.persons.id, personId));
-    
+
     if (!person) {
       throw new NotFoundException(`Person with ID ${personId} not found`);
     }
-    
+
     // Check if the tag is already associated with the person
     const [existingRelation] = await this.db
       .select()
@@ -121,11 +129,11 @@ export class TagsService {
           eq(schema.personToTag.tagId, tagId)
         )
       );
-    
+
     if (existingRelation) {
       return existingRelation;
     }
-    
+
     // Add the tag to the person
     const [relation] = await this.db
       .insert(schema.personToTag)
@@ -134,7 +142,7 @@ export class TagsService {
         tagId,
       })
       .returning();
-    
+
     return relation;
   }
 
@@ -142,6 +150,14 @@ export class TagsService {
    * Remove a tag from a person
    */
   async removeTagFromPerson(tagId: string, personId: string) {
+    // Validate tagId and personId
+    if (!tagId) {
+      throw new BadRequestException('Tag ID is required');
+    }
+    if (!personId) {
+      throw new BadRequestException('Person ID is required');
+    }
+
     const [relation] = await this.db
       .delete(schema.personToTag)
       .where(
@@ -151,11 +167,11 @@ export class TagsService {
         )
       )
       .returning();
-    
+
     if (!relation) {
       throw new NotFoundException(`Tag with ID ${tagId} is not associated with person with ID ${personId}`);
     }
-    
+
     return relation;
   }
 
@@ -163,22 +179,30 @@ export class TagsService {
    * Add a tag to a project
    */
   async addTagToProject(tagId: string, projectId: string) {
+    // Validate tagId and projectId
+    if (!tagId) {
+      throw new BadRequestException('Tag ID is required');
+    }
+    if (!projectId) {
+      throw new BadRequestException('Project ID is required');
+    }
+
     // Check if the tag exists and is of type PROJECT
     const tag = await this.findById(tagId);
     if (tag.type !== 'PROJECT') {
-      throw new Error(`Tag with ID ${tagId} is not of type PROJECT`);
+      throw new BadRequestException(`Tag with ID ${tagId} is not of type PROJECT`);
     }
-    
+
     // Check if the project exists
     const [project] = await this.db
       .select()
       .from(schema.projects)
       .where(eq(schema.projects.id, projectId));
-    
+
     if (!project) {
       throw new NotFoundException(`Project with ID ${projectId} not found`);
     }
-    
+
     // Check if the tag is already associated with the project
     const [existingRelation] = await this.db
       .select()
@@ -189,11 +213,11 @@ export class TagsService {
           eq(schema.projectToTag.tagId, tagId)
         )
       );
-    
+
     if (existingRelation) {
       return existingRelation;
     }
-    
+
     // Add the tag to the project
     const [relation] = await this.db
       .insert(schema.projectToTag)
@@ -202,7 +226,7 @@ export class TagsService {
         tagId,
       })
       .returning();
-    
+
     return relation;
   }
 
@@ -210,6 +234,14 @@ export class TagsService {
    * Remove a tag from a project
    */
   async removeTagFromProject(tagId: string, projectId: string) {
+    // Validate tagId and projectId
+    if (!tagId) {
+      throw new BadRequestException('Tag ID is required');
+    }
+    if (!projectId) {
+      throw new BadRequestException('Project ID is required');
+    }
+
     const [relation] = await this.db
       .delete(schema.projectToTag)
       .where(
@@ -219,11 +251,11 @@ export class TagsService {
         )
       )
       .returning();
-    
+
     if (!relation) {
       throw new NotFoundException(`Tag with ID ${tagId} is not associated with project with ID ${projectId}`);
     }
-    
+
     return relation;
   }
 
@@ -231,16 +263,21 @@ export class TagsService {
    * Get all tags for a person
    */
   async getTagsForPerson(personId: string) {
+    // Validate personId
+    if (!personId) {
+      throw new BadRequestException('Person ID is required');
+    }
+
     // Check if the person exists
     const [person] = await this.db
       .select()
       .from(schema.persons)
       .where(eq(schema.persons.id, personId));
-    
+
     if (!person) {
       throw new NotFoundException(`Person with ID ${personId} not found`);
     }
-    
+
     // Get all tags for the person
     return this.db
       .select({
@@ -255,16 +292,21 @@ export class TagsService {
    * Get all tags for a project
    */
   async getTagsForProject(projectId: string) {
+    // Validate projectId
+    if (!projectId) {
+      throw new BadRequestException('Project ID is required');
+    }
+
     // Check if the project exists
     const [project] = await this.db
       .select()
       .from(schema.projects)
       .where(eq(schema.projects.id, projectId));
-    
+
     if (!project) {
       throw new NotFoundException(`Project with ID ${projectId} not found`);
     }
-    
+
     // Get all tags for the project
     return this.db
       .select({
@@ -274,4 +316,4 @@ export class TagsService {
       .innerJoin(schema.tags, eq(schema.projectToTag.tagId, schema.tags.id))
       .where(eq(schema.projectToTag.projectId, projectId));
   }
-}
\ No newline at end of file
+}