diff --git a/src/Bundle/ChillPersonBundle/PersonIdentifier/Identifier/StringIdentifier.php b/src/Bundle/ChillPersonBundle/PersonIdentifier/Identifier/StringIdentifier.php
index 9979d0f83..4a032a226 100644
--- a/src/Bundle/ChillPersonBundle/PersonIdentifier/Identifier/StringIdentifier.php
+++ b/src/Bundle/ChillPersonBundle/PersonIdentifier/Identifier/StringIdentifier.php
@@ -26,7 +26,7 @@ final readonly class StringIdentifier implements PersonIdentifierEngineInterface
 
     public function canonicalizeValue(array $value, PersonIdentifierDefinition $definition): ?string
     {
-        return $value['content'] ?? '';
+        return trim($value['content'] ?? '');
     }
 
     public function buildForm(FormBuilderInterface $builder, PersonIdentifierDefinition $personIdentifierDefinition): void
@@ -36,7 +36,7 @@ final readonly class StringIdentifier implements PersonIdentifierEngineInterface
 
     public function renderAsString(?PersonIdentifier $identifier, PersonIdentifierDefinition $definition): string
     {
-        return $identifier?->getValue()['content'] ?? '';
+        return trim($identifier?->getValue()['content'] ?? '');
     }
 
     public function isEmpty(PersonIdentifier $identifier): bool
diff --git a/src/Bundle/ChillPersonBundle/PersonIdentifier/Validator/RequiredIdentifierConstraint.php b/src/Bundle/ChillPersonBundle/PersonIdentifier/Validator/RequiredIdentifierConstraint.php
new file mode 100644
index 000000000..872dd8113
--- /dev/null
+++ b/src/Bundle/ChillPersonBundle/PersonIdentifier/Validator/RequiredIdentifierConstraint.php
@@ -0,0 +1,27 @@
+<?php
+
+declare(strict_types=1);
+
+/*
+ * Chill is a software for social workers
+ *
+ * For the full copyright and license information, please view
+ * the LICENSE file that was distributed with this source code.
+ */
+
+namespace Chill\PersonBundle\PersonIdentifier\Validator;
+
+use Symfony\Component\Validator\Constraint;
+
+/**
+ * Test that the required constraints are present.
+ */
+class RequiredIdentifierConstraint extends Constraint
+{
+    public string $message = 'This identifier must be set';
+
+    public function getTargets(): string
+    {
+        return self::PROPERTY_CONSTRAINT;
+    }
+}
diff --git a/src/Bundle/ChillPersonBundle/PersonIdentifier/Validator/RequiredIdentifierConstraintValidator.php b/src/Bundle/ChillPersonBundle/PersonIdentifier/Validator/RequiredIdentifierConstraintValidator.php
new file mode 100644
index 000000000..c8f4ea2a6
--- /dev/null
+++ b/src/Bundle/ChillPersonBundle/PersonIdentifier/Validator/RequiredIdentifierConstraintValidator.php
@@ -0,0 +1,54 @@
+<?php
+
+declare(strict_types=1);
+
+/*
+ * Chill is a software for social workers
+ *
+ * For the full copyright and license information, please view
+ * the LICENSE file that was distributed with this source code.
+ */
+
+namespace Chill\PersonBundle\PersonIdentifier\Validator;
+
+use Chill\PersonBundle\Entity\Identifier\IdentifierPresenceEnum;
+use Chill\PersonBundle\Entity\Identifier\PersonIdentifier;
+use Chill\PersonBundle\PersonIdentifier\PersonIdentifierManagerInterface;
+use Doctrine\Common\Collections\Collection;
+use Symfony\Component\Validator\Constraint;
+use Symfony\Component\Validator\ConstraintValidator;
+use Symfony\Component\Validator\Exception\UnexpectedTypeException;
+use Symfony\Component\Validator\Exception\UnexpectedValueException;
+
+final class RequiredIdentifierConstraintValidator extends ConstraintValidator
+{
+    public function __construct(private readonly PersonIdentifierManagerInterface $identifierManager) {}
+
+    public function validate($value, Constraint $constraint)
+    {
+        if (!$constraint instanceof RequiredIdentifierConstraint) {
+            throw new UnexpectedTypeException($constraint, RequiredIdentifierConstraint::class);
+        }
+
+        if (!$value instanceof Collection) {
+            throw new UnexpectedValueException($value, Collection::class);
+        }
+
+        foreach ($this->identifierManager->getWorkers() as $worker) {
+            if (IdentifierPresenceEnum::REQUIRED !== $worker->getDefinition()->getPresence()) {
+                continue;
+            }
+
+            $identifier = $value->findFirst(fn (int $key, PersonIdentifier $identifier) => $identifier->getDefinition() === $worker->getDefinition());
+
+            if (null === $identifier || $worker->isEmpty($identifier)) {
+                $this->context->buildViolation($constraint->message)
+                    ->setParameter('{{ value }}', $worker->renderAsString($identifier))
+                    ->setParameter('definition_id', (string) $worker->getDefinition()->getId())
+                    ->atPath('identifiers')
+                    ->setCode('c08b7b32-947f-11f0-8608-9b8560e9bf05')
+                    ->addViolation();
+            }
+        }
+    }
+}
diff --git a/src/Bundle/ChillPersonBundle/Tests/PersonIdentifier/Validator/RequiredIdentifierConstraintValidatorTest.php b/src/Bundle/ChillPersonBundle/Tests/PersonIdentifier/Validator/RequiredIdentifierConstraintValidatorTest.php
new file mode 100644
index 000000000..31df89315
--- /dev/null
+++ b/src/Bundle/ChillPersonBundle/Tests/PersonIdentifier/Validator/RequiredIdentifierConstraintValidatorTest.php
@@ -0,0 +1,133 @@
+<?php
+
+declare(strict_types=1);
+
+/*
+ * Chill is a software for social workers
+ *
+ * For the full copyright and license information, please view
+ * the LICENSE file that was distributed with this source code.
+ */
+
+namespace Chill\PersonBundle\Tests\PersonIdentifier\Validator;
+
+use Chill\PersonBundle\Entity\Identifier\IdentifierPresenceEnum;
+use Chill\PersonBundle\Entity\Identifier\PersonIdentifier;
+use Chill\PersonBundle\Entity\Identifier\PersonIdentifierDefinition;
+use Chill\PersonBundle\PersonIdentifier\PersonIdentifierEngineInterface;
+use Chill\PersonBundle\PersonIdentifier\PersonIdentifierManagerInterface;
+use Chill\PersonBundle\PersonIdentifier\PersonIdentifierWorker;
+use Chill\PersonBundle\PersonIdentifier\Validator\RequiredIdentifierConstraint;
+use Chill\PersonBundle\PersonIdentifier\Validator\RequiredIdentifierConstraintValidator;
+use Doctrine\Common\Collections\ArrayCollection;
+use PHPUnit\Framework\Attributes\CoversClass;
+use Symfony\Component\Validator\Constraints\NotBlank;
+use Symfony\Component\Validator\Exception\UnexpectedTypeException;
+use Symfony\Component\Validator\Exception\UnexpectedValueException;
+use Symfony\Component\Validator\Test\ConstraintValidatorTestCase;
+use Prophecy\PhpUnit\ProphecyTrait;
+use Prophecy\Argument;
+
+/**
+ * @internal
+ */
+#[CoversClass(RequiredIdentifierConstraintValidator::class)]
+final class RequiredIdentifierConstraintValidatorTest extends ConstraintValidatorTestCase
+{
+    use ProphecyTrait;
+
+    private PersonIdentifierDefinition $requiredDefinition;
+
+    protected function createValidator(): RequiredIdentifierConstraintValidator
+    {
+        $this->requiredDefinition = new PersonIdentifierDefinition(
+            label: ['fr' => 'Identifiant requis'],
+            engine: 'test.engine',
+        );
+        $this->requiredDefinition->setPresence(IdentifierPresenceEnum::REQUIRED);
+        $reflection = new \ReflectionClass($this->requiredDefinition);
+        $id = $reflection->getProperty('id');
+        $id->setValue($this->requiredDefinition, 1);
+
+        // Mock only the required methods of the engine used by the validator through the worker
+        $engineProphecy = $this->prophesize(PersonIdentifierEngineInterface::class);
+        $engineProphecy->isEmpty(Argument::type(PersonIdentifier::class))
+            ->will(function (array $args): bool {
+                /** @var PersonIdentifier $identifier */
+                $identifier = $args[0];
+
+                return '' === trim($identifier->getValue()['content'] ?? '');
+            });
+        $engineProphecy->renderAsString(Argument::any(), Argument::any())
+            ->will(function (array $args): string {
+                /** @var PersonIdentifier|null $identifier */
+                $identifier = $args[0] ?? null;
+
+                return $identifier?->getValue()['content'] ?? '';
+            });
+
+        $worker = new PersonIdentifierWorker($engineProphecy->reveal(), $this->requiredDefinition);
+
+        // Mock only the required method used by the validator
+        $managerProphecy = $this->prophesize(PersonIdentifierManagerInterface::class);
+        $managerProphecy->getWorkers()->willReturn([$worker]);
+
+        return new RequiredIdentifierConstraintValidator($managerProphecy->reveal());
+    }
+
+    public function testThrowsOnNonCollectionValue(): void
+    {
+        $this->expectException(UnexpectedValueException::class);
+        $this->validator->validate(new \stdClass(), new RequiredIdentifierConstraint());
+    }
+
+    public function testThrowsOnInvalidConstraintType(): void
+    {
+        $this->expectException(UnexpectedTypeException::class);
+        // Provide a valid Collection value so the type check reaches the constraint check
+        $this->validator->validate(new ArrayCollection(), new NotBlank());
+    }
+
+    public function testNoViolationWhenRequiredIdentifierPresentAndNotEmpty(): void
+    {
+        $identifier = new PersonIdentifier($this->requiredDefinition);
+        $identifier->setValue(['content' => 'ABC']);
+
+        $collection = new ArrayCollection([$identifier]);
+
+        $this->validator->validate($collection, new RequiredIdentifierConstraint());
+
+        $this->assertNoViolation();
+    }
+
+    public function testViolationWhenRequiredIdentifierMissing(): void
+    {
+        $collection = new ArrayCollection();
+
+        $this->validator->validate($collection, new RequiredIdentifierConstraint());
+
+        $this->buildViolation('This identifier must be set')
+            ->atPath('property.path.identifiers')
+            ->setParameter('{{ value }}', '')
+            ->setParameter('definition_id', '1')
+            ->setCode('c08b7b32-947f-11f0-8608-9b8560e9bf05')
+            ->assertRaised();
+    }
+
+    public function testViolationWhenRequiredIdentifierIsEmpty(): void
+    {
+        $identifier = new PersonIdentifier($this->requiredDefinition);
+        $identifier->setValue(['content' => '   ']);
+
+        $collection = new ArrayCollection([$identifier]);
+
+        $this->validator->validate($collection, new RequiredIdentifierConstraint());
+
+        $this->buildViolation('This identifier must be set')
+            ->atPath('property.path.identifiers')
+            ->setParameter('{{ value }}', '   ')
+            ->setParameter('definition_id', '1')
+            ->setCode('c08b7b32-947f-11f0-8608-9b8560e9bf05')
+            ->assertRaised();
+    }
+}