diff --git a/app_new/lib_ext/vacances_scolaires.py b/app_new/lib_ext/vacances_scolaires.py
index b354454..e25f161 100644
--- a/app_new/lib_ext/vacances_scolaires.py
+++ b/app_new/lib_ext/vacances_scolaires.py
@@ -75,6 +75,19 @@ def import_vacances_scolaires(zone="A", annee=None, user_id=None):
     if not vacances:
         # Données de fallback si l'API n'est pas accessible
         vacances = get_vacances_fallback(zone, annee)
+
+    # Les périodes importées représentent une seule zone de référence.
+    # Lors d'un changement de zone, retirer uniquement les anciennes
+    # périodes issues d'un import officiel (jamais les périodes manuelles).
+    imported_closures = CollegeClosure.query.filter(
+        CollegeClosure.closure_type == "vacances_scolaires",
+        CollegeClosure.notes.like("Zone académique % — import officiel"),
+    ).all()
+    for existing in imported_closures:
+        if not (existing.notes or "").startswith(f"Zone académique {zone} "):
+            db.session.delete(existing)
+    if imported_closures:
+        db.session.flush()
     
     ajoutees = 0
     ignorees = 0
diff --git a/app_new/planning/templates/planning/time_tracking.html b/app_new/planning/templates/planning/time_tracking.html
index 03f09d4..128ab12 100644
--- a/app_new/planning/templates/planning/time_tracking.html
+++ b/app_new/planning/templates/planning/time_tracking.html
@@ -34,7 +34,7 @@
         {% for day_num, day_name in days.items() %}<div class="col-md-6"><form method="post" action="{{ url_for('planning.assign_time_template') }}" class="input-group"><span class="input-group-text">{{ day_name }}</span><input type="hidden" name="day_of_week" value="{{ day_num }}"><select class="form-select" name="template_id" onchange="this.form.submit()"><option value="">Non travaillé</option>{% for template in templates %}<option value="{{ template.id }}" {% if assignments.get(day_num) and assignments[day_num].template_id == template.id %}selected{% endif %}>{{ template.name }}</option>{% endfor %}</select></form></div>{% endfor %}
       </div></div></div>
 
-      <div class="card mb-3"><div class="card-header"><strong>Importer les calendriers</strong></div><div class="card-body"><div class="row g-2"><div class="col-md-6"><form method="post" action="{{ url_for('planning.import_school_vacations') }}"><input type="hidden" name="csrf_token" value="{{ csrf_token() }}"><input type="hidden" name="year" value="{{ year }}"><div class="input-group"><select class="form-select" name="zone"><option value="B">Zone B (Seine-et-Marne)</option><option value="A">Zone A</option><option value="C">Zone C</option></select><button class="btn btn-outline-primary">Importer vacances</button></div></form></div><div class="col-md-6"><form method="post" action="{{ url_for('planning.import_public_holidays') }}"><input type="hidden" name="csrf_token" value="{{ csrf_token() }}"><input type="hidden" name="year" value="{{ year }}"><button class="btn btn-outline-primary">Importer jours fériés {{ year }}</button></form></div></div></div></div>
+      <div class="card mb-3"><div class="card-header"><strong>Importer les calendriers</strong></div><div class="card-body"><div class="row g-2"><div class="col-md-6"><form method="post" action="{{ url_for('planning.import_school_vacations') }}"><input type="hidden" name="csrf_token" value="{{ csrf_token() }}"><input type="hidden" name="year" value="{{ year }}"><div class="input-group"><select class="form-select" name="zone"><option value="C" selected>Zone C</option><option value="B">Zone B</option><option value="A">Zone A</option></select><button class="btn btn-outline-primary">Importer vacances</button></div><small class="text-muted">Changer de zone remplace les périodes scolaires importées pour l’autre zone.</small></form></div><div class="col-md-6"><form method="post" action="{{ url_for('planning.import_public_holidays') }}"><input type="hidden" name="csrf_token" value="{{ csrf_token() }}"><input type="hidden" name="year" value="{{ year }}"><button class="btn btn-outline-primary">Importer jours fériés {{ year }}</button></form></div></div></div></div>
 
       <div class="card mb-3"><div class="card-header"><strong>Permanences dans les vacances</strong><small class="d-block text-muted">Sélectionnez plusieurs dates puis l’horaire type à appliquer.</small></div><div class="card-body"><form method="post" action="{{ url_for('planning.save_permanences') }}"><input type="hidden" name="csrf_token" value="{{ csrf_token() }}"><input type="hidden" name="year" value="{{ year }}"><div class="row g-2 align-items-end"><div class="col-md-8"><label class="form-label">Horaire type</label><select class="form-select" name="template_id" required><option value="">Choisir…</option>{% for template in templates %}<option value="{{ template.id }}">{{ template.name }} ({{ template.start_time.strftime('%H:%M') }}–{{ template.end_time.strftime('%H:%M') }})</option>{% endfor %}</select></div><div class="col-md-4"><button class="btn btn-success w-100" {% if not templates %}disabled{% endif %}>Affecter les dates sélectionnées</button></div></div><div class="row g-2 mt-2">{% for option in permanence_options %}<div class="col-xl-3 col-lg-4 col-md-6"><label class="border rounded p-2 d-block"><input type="checkbox" name="work_dates" value="{{ option.date.isoformat() }}" {% if option.entry %}checked{% endif %}> <strong>{{ option.date.strftime('%d/%m/%Y') }}</strong><br><small>{{ option.closure.name }}{% if option.entry and option.entry.template %} · {{ option.entry.template.name }}{% endif %}</small></label></div>{% else %}<div class="col-12 text-muted">Aucune période de vacances importée pour cette période. Importez d’abord le calendrier scolaire.</div>{% endfor %}</div></form></div></div>
 
diff --git a/app_new/planning/time_tracking.py b/app_new/planning/time_tracking.py
index 7795fae..e614c9d 100644
--- a/app_new/planning/time_tracking.py
+++ b/app_new/planning/time_tracking.py
@@ -227,7 +227,7 @@ def save_time_entry():
 def import_school_vacations():
     from app_new.lib_ext.vacances_scolaires import import_vacances_scolaires
     year = request.form.get("year", date.today().year, type=int)
-    added, ignored, errors = import_vacances_scolaires(request.form.get("zone", "B"), year, current_user.id)
+    added, ignored, errors = import_vacances_scolaires(request.form.get("zone", "C"), year, current_user.id)
     flash(f"Vacances importées : {added} ajoutée(s), {ignored} déjà présente(s)." + (f" {len(errors)} erreur(s)." if errors else ""), "warning" if errors else "success")
     return _redirect(year)