diff --git a/src/Symfony/Component/Validator/Constraints/Bic.php b/src/Symfony/Component/Validator/Constraints/Bic.php
index 625fb7213241..22640bedfc79 100644
--- a/src/Symfony/Component/Validator/Constraints/Bic.php
+++ b/src/Symfony/Component/Validator/Constraints/Bic.php
@@ -15,6 +15,7 @@
 use Symfony\Component\PropertyAccess\PropertyAccess;
 use Symfony\Component\Validator\Constraint;
 use Symfony\Component\Validator\Exception\ConstraintDefinitionException;
+use Symfony\Component\Validator\Exception\InvalidArgumentException;
 use Symfony\Component\Validator\Exception\LogicException;
 
 /**
@@ -27,6 +28,14 @@
 #[\Attribute(\Attribute::TARGET_PROPERTY | \Attribute::TARGET_METHOD | \Attribute::IS_REPEATABLE)]
 class Bic extends Constraint
 {
+    public const VALIDATION_MODE_STRICT = 'strict';
+    public const VALIDATION_MODE_CASE_INSENSITIVE = 'case-insensitive';
+
+    public const VALIDATION_MODES = [
+        self::VALIDATION_MODE_STRICT,
+        self::VALIDATION_MODE_CASE_INSENSITIVE,
+    ];
+
     public const INVALID_LENGTH_ERROR = '66dad313-af0b-4214-8566-6c799be9789c';
     public const INVALID_CHARACTERS_ERROR = 'f424c529-7add-4417-8f2d-4b656e4833e2';
     /**
@@ -49,18 +58,34 @@ class Bic extends Constraint
     public string $ibanMessage = 'This Business Identifier Code (BIC) is not associated with IBAN {{ iban }}.';
     public ?string $iban = null;
     public ?string $ibanPropertyPath = null;
+    public ?string $mode = self::VALIDATION_MODE_STRICT;
 
     /**
      * @param array<string,mixed>|null $options
      * @param string|null              $iban             An IBAN value to validate that its country code is the same as the BIC's one
      * @param string|null              $ibanPropertyPath Property path to the IBAN value when validating objects
      * @param string[]|null            $groups
+     * @param string|null              $mode             The mode used to validate the BIC; pass null to use the default mode (strict)
      */
-    public function __construct(?array $options = null, ?string $message = null, ?string $iban = null, ?string $ibanPropertyPath = null, ?string $ibanMessage = null, ?array $groups = null, mixed $payload = null)
-    {
+    public function __construct(
+        ?array $options = null,
+        ?string $message = null,
+        ?string $iban = null,
+        ?string $ibanPropertyPath = null,
+        ?string $ibanMessage = null,
+        ?array $groups = null,
+        mixed $payload = null,
+        ?string $mode = null,
+    ) {
         if (!class_exists(Countries::class)) {
             throw new LogicException('The Intl component is required to use the Bic constraint. Try running "composer require symfony/intl".');
         }
+        if (\is_array($options) && \array_key_exists('mode', $options) && !\in_array($options['mode'], self::VALIDATION_MODES, true)) {
+            throw new InvalidArgumentException('The "mode" parameter value is not valid.');
+        }
+        if (null !== $mode && !\in_array($mode, self::VALIDATION_MODES, true)) {
+            throw new InvalidArgumentException('The "mode" parameter value is not valid.');
+        }
 
         parent::__construct($options, $groups, $payload);
 
@@ -68,6 +93,7 @@ public function __construct(?array $options = null, ?string $message = null, ?st
         $this->ibanMessage = $ibanMessage ?? $this->ibanMessage;
         $this->iban = $iban ?? $this->iban;
         $this->ibanPropertyPath = $ibanPropertyPath ?? $this->ibanPropertyPath;
+        $this->mode = $mode ?? $this->mode;
 
         if (null !== $this->iban && null !== $this->ibanPropertyPath) {
             throw new ConstraintDefinitionException('The "iban" and "ibanPropertyPath" options of the Iban constraint cannot be used at the same time.');
diff --git a/src/Symfony/Component/Validator/Constraints/BicValidator.php b/src/Symfony/Component/Validator/Constraints/BicValidator.php
index 19b88b68937a..d0d1b5084185 100644
--- a/src/Symfony/Component/Validator/Constraints/BicValidator.php
+++ b/src/Symfony/Component/Validator/Constraints/BicValidator.php
@@ -100,6 +100,9 @@ public function validate(mixed $value, Constraint $constraint): void
         }
 
         $bicCountryCode = substr($canonicalize, 4, 2);
+        if (Bic::VALIDATION_MODE_CASE_INSENSITIVE === $constraint->mode) {
+            $bicCountryCode = strtoupper($bicCountryCode);
+        }
         if (!isset(self::BIC_COUNTRY_TO_IBAN_COUNTRY_MAP[$bicCountryCode]) && !Countries::exists($bicCountryCode)) {
             $this->context->buildViolation($constraint->message)
                 ->setParameter('{{ value }}', $this->formatValue($value))
@@ -109,8 +112,8 @@ public function validate(mixed $value, Constraint $constraint): void
             return;
         }
 
-        // should contain uppercase characters only
-        if (strtoupper($canonicalize) !== $canonicalize) {
+        // should contain uppercase characters only in strict mode
+        if (Bic::VALIDATION_MODE_STRICT === $constraint->mode && strtoupper($canonicalize) !== $canonicalize) {
             $this->context->buildViolation($constraint->message)
                 ->setParameter('{{ value }}', $this->formatValue($value))
                 ->setCode(Bic::INVALID_CASE_ERROR)
diff --git a/src/Symfony/Component/Validator/Tests/Constraints/BicValidatorTest.php b/src/Symfony/Component/Validator/Tests/Constraints/BicValidatorTest.php
index 8b3c815423a4..b71c7dac5272 100644
--- a/src/Symfony/Component/Validator/Tests/Constraints/BicValidatorTest.php
+++ b/src/Symfony/Component/Validator/Tests/Constraints/BicValidatorTest.php
@@ -14,6 +14,7 @@
 use Symfony\Component\Validator\Constraints\Bic;
 use Symfony\Component\Validator\Constraints\BicValidator;
 use Symfony\Component\Validator\Exception\ConstraintDefinitionException;
+use Symfony\Component\Validator\Exception\InvalidArgumentException;
 use Symfony\Component\Validator\Exception\UnexpectedValueException;
 use Symfony\Component\Validator\Mapping\ClassMetadata;
 use Symfony\Component\Validator\Mapping\Loader\AttributeLoader;
@@ -301,6 +302,36 @@ public static function getValidBicSpecialCases()
         yield ['CAIXICBBXXX', 'ES79 2100 0813 6101 2345 6789'];
         yield ['CAIXEABBXXX', 'ES79 2100 0813 6101 2345 6789'];
     }
+
+    /**
+     * @dataProvider getValidBicsWithNormalizerToUpper
+     */
+    public function testValidBicsWithNormalizerToUpper($bic)
+    {
+        $this->validator->validate($bic, new Bic(mode: Bic::VALIDATION_MODE_CASE_INSENSITIVE));
+
+        $this->assertNoViolation();
+    }
+
+    public static function getValidBicsWithNormalizerToUpper()
+    {
+        return [
+            ['ASPKAT2LXXX'],
+            ['ASPKat2LXXX'],
+            ['ASPKaT2LXXX'],
+            ['ASPKAt2LXXX'],
+            ['aspkat2lxxx'],
+        ];
+    }
+
+    public function testFailOnInvalidMode()
+    {
+        $this->expectException(InvalidArgumentException::class);
+        $this->validator->validate('ASPKAT2LXXX', new Bic(mode: 'invalid'));
+
+        $this->expectException(InvalidArgumentException::class);
+        $this->validator->validate('ASPKAT2LXXX', new Bic(options: ['mode' => 'invalid']));
+    }
 }
 
 class BicComparisonTestClass
diff --git a/src/Symfony/Component/Validator/Tests/Constraints/IbanValidatorTest.php b/src/Symfony/Component/Validator/Tests/Constraints/IbanValidatorTest.php
index 212d5329f44a..390f106df564 100644
--- a/src/Symfony/Component/Validator/Tests/Constraints/IbanValidatorTest.php
+++ b/src/Symfony/Component/Validator/Tests/Constraints/IbanValidatorTest.php
@@ -53,6 +53,7 @@ public static function getValidIbans()
         return [
             ['CH9300762011623852957'], // Switzerland without spaces
             ['CH93  0076 2011 6238 5295 7'], // Switzerland with multiple spaces
+            ['ch93 0076 2011 6238 5295 7'], // Switzerland lower case
 
             // Country list
             // http://www.rbs.co.uk/corporate/international/g0/guide-to-international-business/regulatory-information/iban/iban-example.ashx