diff --git a/frontend/src/lib/utils.ts b/frontend/src/lib/utils.ts
index 8b4fe98d..51ca79f9 100644
--- a/frontend/src/lib/utils.ts
+++ b/frontend/src/lib/utils.ts
@@ -1,20 +1 @@
-/**
- * Converts an ISO date string (YYYY-MM-DD) to German display format (DD.MM.YYYY).
- * Returns an empty string for invalid or empty input.
- */
-export function isoToGerman(iso: string): string {
-	if (!iso || !/^\d{4}-\d{2}-\d{2}$/.test(iso)) return '';
-	const [y, m, d] = iso.split('-');
-	return `${d}.${m}.${y}`;
-}
-
-/**
- * Converts a German date string (DD.MM.YYYY) to ISO format (YYYY-MM-DD).
- * Returns an empty string for invalid or empty input.
- */
-export function germanToIso(german: string): string {
-	const match = german.match(/^(\d{2})\.(\d{2})\.(\d{4})$/);
-	if (!match) return '';
-	const [, d, m, y] = match;
-	return `${y}-${m}-${d}`;
-}
+export { isoToGerman, germanToIso } from '$lib/utils/date';
diff --git a/frontend/src/lib/utils/date.ts b/frontend/src/lib/utils/date.ts
index 9f8b5c54..c2ab4e8e 100644
--- a/frontend/src/lib/utils/date.ts
+++ b/frontend/src/lib/utils/date.ts
@@ -9,3 +9,44 @@ export function formatDate(isoDate: string): string {
 		year: 'numeric'
 	}).format(new Date(isoDate + 'T12:00:00'));
 }
+
+/**
+ * Converts an ISO date string (YYYY-MM-DD) to German display format (DD.MM.YYYY).
+ * Returns an empty string for invalid or empty input.
+ */
+export function isoToGerman(iso: string): string {
+	if (!iso || !/^\d{4}-\d{2}-\d{2}$/.test(iso)) return '';
+	const [y, m, d] = iso.split('-');
+	return `${d}.${m}.${y}`;
+}
+
+/**
+ * Converts a German date string (DD.MM.YYYY) to ISO format (YYYY-MM-DD).
+ * Returns an empty string for invalid or empty input.
+ */
+export function germanToIso(german: string): string {
+	const match = german.match(/^(\d{2})\.(\d{2})\.(\d{4})$/);
+	if (!match) return '';
+	const [, d, m, y] = match;
+	return `${y}-${m}-${d}`;
+}
+
+/**
+ * Handles a date input event for German-format date fields (DD.MM.YYYY).
+ * Strips non-digits, formats with dots, mutates the input's displayed value,
+ * and returns the display string and its ISO equivalent.
+ */
+export function handleGermanDateInput(e: Event): { display: string; iso: string } {
+	const input = e.target as HTMLInputElement;
+	const digits = input.value.replace(/\D/g, '').slice(0, 8);
+	let display: string;
+	if (digits.length <= 2) {
+		display = digits;
+	} else if (digits.length <= 4) {
+		display = `${digits.slice(0, 2)}.${digits.slice(2)}`;
+	} else {
+		display = `${digits.slice(0, 2)}.${digits.slice(2, 4)}.${digits.slice(4)}`;
+	}
+	input.value = display;
+	return { display, iso: germanToIso(display) };
+}