diff --git a/README.md b/README.md
index 122cb51..422e87d 100644
--- a/README.md
+++ b/README.md
@@ -50,6 +50,24 @@ echo $caseCreated->name; // Display "This is a new case."
 ```
 
 See [dotfile documentation](https://docs.dotfile.com/reference/case-create-one).
+</details>
+
+<details>
+
+<summary>Add tags in an existing case</summary>
+
+```php
+use Dotfile\Model\Case\CaseTags;
+use Dotfile\Model\Case\CaseTagsInput;
+
+$input = new CaseTagsInput();
+$input->caseId = '39cbd6d5-4da5-4d94-ae71-84895c5e552a';
+$input->tags = ['A faire'];
+
+$caseAddTags = $client->case->addTags($input); // Returns an instance of CaseTags
+
+echo $caseAddTags->tags[0]['label']; // Display "A faire"
+```
 
 </details>
 
@@ -103,3 +121,11 @@ echo $individual->lastName; // Display "Parks"
 See [dotfile documentation](https://docs.dotfile.com/reference/individual-create-one).
 
 </details>
+
+### Tests
+
+To launch all the tests:
+
+```php
+make test
+```
diff --git a/src/Exception/DotfileApiException.php b/src/Exception/DotfileApiException.php
index 7fa842a..a8890a4 100644
--- a/src/Exception/DotfileApiException.php
+++ b/src/Exception/DotfileApiException.php
@@ -4,4 +4,6 @@
 
 namespace Dotfile\Exception;
 
-class DotfileApiException extends \Exception {}
+class DotfileApiException extends \Exception
+{
+}
diff --git a/src/Model/Case/CaseTags.php b/src/Model/Case/CaseTags.php
new file mode 100644
index 0000000..26378d1
--- /dev/null
+++ b/src/Model/Case/CaseTags.php
@@ -0,0 +1,18 @@
+<?php
+
+declare(strict_types=1);
+
+namespace Dotfile\Model\Case;
+
+/**
+ * Response when a tag has been added to a case.
+ *
+ * @see https://docs.dotfile.com/reference/case-tag-create-case-tags
+ */
+class CaseTags
+{
+    /**
+     * @var array<string, string>
+     */
+    public array $tags = [];
+}
diff --git a/src/Model/Case/CaseTagsInput.php b/src/Model/Case/CaseTagsInput.php
new file mode 100644
index 0000000..ea5daa5
--- /dev/null
+++ b/src/Model/Case/CaseTagsInput.php
@@ -0,0 +1,23 @@
+<?php
+
+declare(strict_types=1);
+
+namespace Dotfile\Model\Case;
+
+/**
+ * Input used to add a tag for a case.
+ *
+ * @see https://docs.dotfile.com/reference/case-tag-create-case-tags
+ */
+class CaseTagsInput
+{
+    /**
+     * Case id where the case is created.
+     */
+    public string $caseId;
+
+    /**
+     * @var string[]
+     */
+    public ?array $tags;
+}
diff --git a/src/Service/AbstractService.php b/src/Service/AbstractService.php
index 8a15f01..03bbb6f 100644
--- a/src/Service/AbstractService.php
+++ b/src/Service/AbstractService.php
@@ -16,7 +16,8 @@ abstract class AbstractService
     public function __construct(
         protected HttpClientInterface $client,
         protected SerializerInterface $serializer,
-    ) {}
+    ) {
+    }
 
     /**
      * @throws DotfileApiException
diff --git a/src/Service/CaseService.php b/src/Service/CaseService.php
index de4f956..54c47ab 100644
--- a/src/Service/CaseService.php
+++ b/src/Service/CaseService.php
@@ -6,6 +6,8 @@
 
 use Dotfile\Model\Case\CaseCreated;
 use Dotfile\Model\Case\CaseCreateInput;
+use Dotfile\Model\Case\CaseTags;
+use Dotfile\Model\Case\CaseTagsInput;
 use Dotfile\Model\Case\RiskLevel;
 use Symfony\Component\HttpFoundation\Request;
 use Symfony\Component\Serializer\Normalizer\AbstractObjectNormalizer;
@@ -33,4 +35,18 @@ public function create(CaseCreateInput $input): CaseCreated
 
         return $caseCreated;
     }
+
+    public function addTags(CaseTagsInput $input, string $caseId): CaseTags
+    {
+        $body = $this->serializer->serialize($input, 'json', [AbstractObjectNormalizer::SKIP_NULL_VALUES => true]);
+
+        $response = $this->client->request(Request::METHOD_POST, 'cases/'.$caseId.'/tags', [
+            'headers' => [
+                'Content-Type' => 'application/json',
+            ],
+            'body' => $body,
+        ]);
+
+        return $this->serializer->deserialize($this->getContent($response), CaseTags::class, 'json');
+    }
 }
diff --git a/src/Service/TagsCaseService.php b/src/Service/TagsCaseService.php
new file mode 100644
index 0000000..8ff278a
--- /dev/null
+++ b/src/Service/TagsCaseService.php
@@ -0,0 +1,27 @@
+<?php
+
+declare(strict_types=1);
+
+namespace Dotfile\Service;
+
+use Dotfile\Model\Case\CaseTags;
+use Dotfile\Model\Case\CaseTagsInput;
+use Symfony\Component\HttpFoundation\Request;
+use Symfony\Component\Serializer\Normalizer\AbstractObjectNormalizer;
+
+class TagsCaseService extends AbstractService
+{
+    public function create(CaseTagsInput $input, string $caseId): CaseTags
+    {
+        $body = $this->serializer->serialize($input, 'json', [AbstractObjectNormalizer::SKIP_NULL_VALUES => true]);
+
+        $response = $this->client->request(Request::METHOD_POST, 'cases/'.$caseId.'/tags', [
+            'headers' => [
+                'Content-Type' => 'application/json',
+            ],
+            'body' => $body,
+        ]);
+
+        return $this->serializer->deserialize($this->getContent($response), CaseTags::class, 'json');
+    }
+}
diff --git a/tests/FunctionalTests/CaseAddTagsTest.php b/tests/FunctionalTests/CaseAddTagsTest.php
new file mode 100644
index 0000000..76fa560
--- /dev/null
+++ b/tests/FunctionalTests/CaseAddTagsTest.php
@@ -0,0 +1,34 @@
+<?php
+
+declare(strict_types=1);
+
+namespace Dotfile\Tests\FunctionalTests;
+
+use Dotfile\DotfileClient;
+use Dotfile\Model\Case\CaseTags;
+use Dotfile\Model\Case\CaseTagsInput;
+use PHPUnit\Framework\TestCase;
+use Symfony\Component\HttpClient\MockHttpClient;
+use Symfony\Component\HttpClient\Response\MockResponse;
+
+class CaseAddTagsTest extends TestCase
+{
+    public function testCaseCreateWithMinimumValidData(): void
+    {
+        $client = new DotfileClient(new MockHttpClient([
+            new MockResponse((string) file_get_contents(__DIR__.'/../fixtures/case_add_tags_with_minimal_data_response.json')),
+        ]));
+
+        $input = new CaseTagsInput();
+        $input->caseId = '39cbd6d5-4da5-4d94-ae71-84895c5e552a';
+        $input->tags = ['A faire'];
+
+        $caseAddTags = $client->case->addTags($input, $input->caseId);
+
+        $this->assertInstanceOf(CaseTags::class, $caseAddTags);
+        $this->assertSame([
+            'id' => 'ea5c5935-2ec8-4519-a526-7ab25c71ac4e',
+            'label' => 'A faire',
+        ], current($caseAddTags->tags));
+    }
+}
diff --git a/tests/fixtures/case_add_tags_with_minimal_data_response.json b/tests/fixtures/case_add_tags_with_minimal_data_response.json
new file mode 100644
index 0000000..ab3d862
--- /dev/null
+++ b/tests/fixtures/case_add_tags_with_minimal_data_response.json
@@ -0,0 +1,8 @@
+{
+  "tags": [
+    {
+      "id": "ea5c5935-2ec8-4519-a526-7ab25c71ac4e",
+      "label": "A faire"
+    }
+  ]
+}
\ No newline at end of file