diff --git a/src/Entity/ApplicationFormSubmission.php b/src/Entity/ApplicationFormSubmission.php
index 3975c13..63968c7 100644
--- a/src/Entity/ApplicationFormSubmission.php
+++ b/src/Entity/ApplicationFormSubmission.php
@@ -208,8 +208,9 @@ class ApplicationFormSubmission implements TimestampableEntityInterface
 
     /**
      * The validated payload as a row. Called with a DTO that passed validation - submittedAt is
-     * parseable and gender is one of F/M/D by then, which is why the constructor can insist on
-     * both.
+     * parseable and gender is one of F/M/D by then (the payload may say W for female;
+     * ApplicationFormSubmissionDto::getGender() has folded it into F), which is why the
+     * constructor can insist on both.
      *
      * The raw payload is passed in separately because the DTO no longer has it: the resolver
      * drops every key the DTO has no property for, and those are the mapped fields the TYPO3
@@ -220,7 +221,7 @@ class ApplicationFormSubmission implements TimestampableEntityInterface
      */
     public static function fromDto(ApplicationFormSubmissionDto $dto, array $payload = []): self
     {
-        $submission = new self($dto->form, $dto->formLabel, $dto->getSubmittedAt(), (string) $dto->gender);
+        $submission = new self($dto->form, $dto->formLabel, $dto->getSubmittedAt(), (string) $dto->getGender());
 
         return $submission
             ->setPageUid($dto->getPageUid())
diff --git a/src/Model/ApplicationFormSubmissionDto.php b/src/Model/ApplicationFormSubmissionDto.php
index b6163bc..459dd67 100644
--- a/src/Model/ApplicationFormSubmissionDto.php
+++ b/src/Model/ApplicationFormSubmissionDto.php
@@ -39,10 +39,24 @@ use Symfony\Component\Validator\Context\ExecutionContextInterface;
 class ApplicationFormSubmissionDto
 {
     /**
+     * The stored vocabulary. W is not in here: it is accepted on the wire and folded into F by
+     * getGender(), so nothing downstream ever sees two spellings of the same gender.
+     *
      * @var list<string>
      */
     public const GENDERS = ['F', 'M', 'D'];
 
+    /**
+     * What a payload may say, before case is folded. The TYPO3 forms are German and some of them
+     * post the German W for female; refusing it - or refusing a lowercase w - would cost a whole
+     * application over a spelling. Checked by validateGender() rather than Assert\Choice, because
+     * Choice compares case-sensitively. Read the gender back through getGender(), never off the
+     * property.
+     *
+     * @var list<string>
+     */
+    public const ACCEPTED_GENDERS = ['F', 'W', 'M', 'D'];
+
     public const MAX_DETAIL_LABEL_LENGTH = 255;
 
     public const MAX_DETAIL_VALUE_LENGTH = 65535;
@@ -86,9 +100,11 @@ class ApplicationFormSubmissionDto
         #[Assert\Date(message: 'birthDate must be a date in the format YYYY-MM-DD.')]
         public readonly ?string $birthDate = null,
         // The application's own vocabulary, not BusPro's: ApplicationFormSubmission::toPayload()
-        // maps F to W on the way out, exactly as Teamer::toPayload() does.
+        // maps F to W on the way out, exactly as Teamer::toPayload() does. W is accepted on the
+        // way in as the German spelling of F, in either case, and normalised by getGender() - the
+        // storage stays F/M/D, and the W that reaches BusPro is the one toPayload() puts there.
+        // Validated by validateGender(), not Assert\Choice.
         #[Assert\NotBlank(message: 'gender must not be empty.')]
-        #[Assert\Choice(choices: self::GENDERS, message: 'gender must be one of F, M or D.')]
         public readonly ?string $gender = null,
         // The whole postal address, required together. Street and postcode are BusPro's own
         // Pflichtfelder for a new address (errors 891 and 890), so a submission without them is one
@@ -180,6 +196,27 @@ class ApplicationFormSubmissionDto
         }
     }
 
+    /**
+     * The same reasoning as validateEu(): getGender() folds case and the German W away, and what
+     * survives that must be one of the three the application stores. Anything else is a 400 with
+     * the vocabulary named, rather than a row nothing downstream can read.
+     */
+    #[Assert\Callback]
+    public function validateGender(ExecutionContextInterface $executionContext): void
+    {
+        if (null === $this->gender || '' === $this->gender) {
+            return;
+        }
+
+        if (!in_array($this->getGender(), self::GENDERS, true)) {
+            $executionContext
+                ->buildViolation('gender must be one of F, W, M or D.')
+                ->atPath('gender')
+                ->addViolation()
+            ;
+        }
+    }
+
     #[Assert\Callback]
     public function validateDetails(ExecutionContextInterface $executionContext): void
     {
@@ -240,6 +277,26 @@ class ApplicationFormSubmissionDto
         };
     }
 
+    /**
+     * The gender as it is stored: upper-cased, with the German W for female folded into F. A form
+     * posts "w" as readily as "W" and neither spelling is worth an application, so case is folded
+     * here rather than demanded of the sender - the same reasoning as isEu() and getPageUid().
+     *
+     * Called by validateGender() as well, so this runs on unvalidated input: it returns whatever
+     * the payload said, upper-cased, and it is validateGender() that decides whether that is one
+     * of GENDERS. Everything after validation sees only F, M, D or null.
+     */
+    public function getGender(): ?string
+    {
+        if (null === $this->gender) {
+            return null;
+        }
+
+        $gender = strtoupper(trim($this->gender));
+
+        return 'W' === $gender ? 'F' : $gender;
+    }
+
     public function getPageUid(): ?int
     {
         if (null === $this->pageUid) {
diff --git a/tests/Controller/Api/ApplicationFormControllerTest.php b/tests/Controller/Api/ApplicationFormControllerTest.php
index 17c83d8..7f94011 100644
--- a/tests/Controller/Api/ApplicationFormControllerTest.php
+++ b/tests/Controller/Api/ApplicationFormControllerTest.php
@@ -359,6 +359,50 @@ class ApplicationFormControllerTest extends WebTestCase
         }
     }
 
+    /**
+     * The German spelling of female. The forms are German and some of them post W; it is accepted
+     * and stored as F, so the row, the provisioned teamer and the payload all read the same
+     * whichever spelling arrived.
+     */
+    public function testTheGermanWIsAcceptedAndStoredAsF(): void
+    {
+        $this->post(['gender' => 'W'] + $this->payload());
+
+        $this->assertSame(Response::HTTP_ACCEPTED, $this->client->getResponse()->getStatusCode());
+
+        $submission = $this->lastSubmission();
+
+        $this->assertSame('F', $submission->getGender());
+        $this->assertSame('W', $submission->toPayload()['geschlecht']);
+        $this->assertSame('W', $submission->getPayload()['gender'] ?? null);
+    }
+
+    /**
+     * Case is the sender's business, not a reason to lose an application: every spelling a form
+     * can post lands on the same stored value.
+     *
+     * @dataProvider genderSpellings
+     */
+    public function testAGenderIsReadWhateverItsCase(string $posted, string $stored): void
+    {
+        $this->post(['gender' => $posted] + $this->payload());
+
+        $this->assertSame(Response::HTTP_ACCEPTED, $this->client->getResponse()->getStatusCode());
+        $this->assertSame($stored, $this->lastSubmission()->getGender());
+    }
+
+    /**
+     * @return iterable<string, array{string, string}>
+     */
+    public static function genderSpellings(): iterable
+    {
+        yield 'lowercase f' => ['f', 'F'];
+        yield 'lowercase w' => ['w', 'F'];
+        yield 'lowercase m' => ['m', 'M'];
+        yield 'lowercase d' => ['d', 'D'];
+        yield 'padded' => [' W ', 'F'];
+    }
+
     /**
      * The mapped vocabulary grows on the website side without a release here. An unknown key is
      * ignored, and kept in the raw payload so it can be mapped later without losing the answers