diff --git a/itou/common_apps/address/departments.py b/itou/common_apps/address/departments.py
index 58692781beb..9cc13b6fec8 100644
--- a/itou/common_apps/address/departments.py
+++ b/itou/common_apps/address/departments.py
@@ -155,6 +155,106 @@ def get_department_to_region():
     "75": {"city": "Paris", "max": 75020},
 }
 
+# https://gist.github.com/sunny/13803?permalink_comment_id=4216753#gistcomment-4216753
+DEPARTMENTS_ADJACENCY = {
+    "01": ("38", "39", "69", "71", "73", "74"),
+    "02": ("08", "51", "59", "60", "77", "80"),
+    "03": ("18", "23", "42", "58", "63", "71"),
+    "04": ("05", "06", "13", "26", "83", "84"),
+    "05": ("04", "26", "38", "73"),
+    "06": ("04", "83"),
+    "07": ("26", "30", "38", "42", "43", "48", "84"),
+    "08": ("02", "51", "55"),
+    "09": ("11", "31", "66"),
+    "10": ("21", "51", "52", "77", "89"),
+    "11": ("09", "31", "34", "66", "81"),
+    "12": ("15", "30", "34", "46", "48", "81", "82"),
+    "13": ("04", "30", "83", "84"),
+    "14": ("27", "50", "61", "76"),
+    "15": ("12", "19", "43", "46", "48", "63"),
+    "16": ("17", "24", "79", "86", "87"),
+    "17": ("16", "24", "33", "79", "85"),
+    "18": ("03", "23", "36", "41", "45", "58"),
+    "19": ("15", "23", "24", "46", "63", "87"),
+    "2A": ("2B"),
+    "2B": ("2A"),
+    "21": ("10", "39", "52", "58", "70", "71", "89"),
+    "22": ("29", "35", "56"),
+    "23": ("03", "18", "19", "36", "63", "87"),
+    "24": ("16", "17", "19", "33", "46", "47", "87"),
+    "25": ("39", "70", "90"),
+    "26": ("04", "05", "07", "38", "84"),
+    "27": ("14", "28", "60", "61", "76", "78", "95"),
+    "28": ("27", "41", "45", "61", "72", "78", "91"),
+    "29": ("22", "56"),
+    "30": ("07", "12", "13", "34", "48", "84"),
+    "31": ("09", "11", "32", "65", "81", "82"),
+    "32": ("31", "40", "47", "64", "65", "82"),
+    "33": ("17", "24", "40", "47"),
+    "34": ("11", "12", "30", "81"),
+    "35": ("22", "44", "49", "50", "53", "56"),
+    "36": ("18", "23", "37", "41", "86", "87"),
+    "37": ("36", "41", "49", "72", "86"),
+    "38": ("01", "05", "07", "26", "42", "69", "73"),
+    "39": ("01", "21", "25", "70", "71"),
+    "40": ("32", "33", "47", "64"),
+    "41": ("18", "28", "36", "37", "45", "72"),
+    "42": ("03", "07", "38", "43", "63", "69", "71"),
+    "43": ("07", "15", "42", "48", "63"),
+    "44": ("35", "49", "56", "85"),
+    "45": ("18", "28", "41", "58", "77", "89", "91"),
+    "46": ("12", "15", "19", "24", "47", "82"),
+    "47": ("24", "32", "33", "40", "46", "82"),
+    "48": ("07", "12", "15", "30", "43"),
+    "49": ("35", "37", "44", "53", "72", "79", "85", "86"),
+    "50": ("14", "35", "53", "61"),
+    "51": ("02", "08", "10", "52", "55", "77"),
+    "52": ("10", "21", "51", "55", "70", "88"),
+    "53": ("35", "49", "50", "61", "72"),
+    "54": ("55", "57", "67", "88"),
+    "55": ("08", "51", "52", "54", "88"),
+    "56": ("22", "29", "35", "44"),
+    "57": ("54", "67"),
+    "58": ("03", "18", "21", "45", "71", "89"),
+    "59": ("02", "62", "80"),
+    "60": ("02", "27", "76", "77", "80", "95"),
+    "61": ("14", "27", "28", "50", "53", "72"),
+    "62": ("59", "80"),
+    "63": ("03", "15", "19", "23", "42", "43"),
+    "64": ("32", "40", "65"),
+    "65": ("31", "32", "64"),
+    "66": ("09", "11"),
+    "67": ("54", "57", "68", "88"),
+    "68": ("67", "88", "90"),
+    "69": ("01", "38", "42", "71"),
+    "70": ("21", "25", "39", "52", "88", "90"),
+    "71": ("01", "03", "21", "39", "42", "58", "69"),
+    "72": ("28", "37", "41", "49", "53", "61"),
+    "73": ("01", "05", "38", "74"),
+    "74": ("01", "73"),
+    "75": ("92", "93", "94"),
+    "76": ("14", "27", "60", "80"),
+    "77": ("02", "10", "45", "51", "60", "89", "91", "93", "94", "95"),
+    "78": ("27", "28", "91", "92", "95"),
+    "79": ("16", "17", "49", "85", "86"),
+    "80": ("02", "59", "60", "62", "76"),
+    "81": ("11", "12", "31", "34", "82"),
+    "82": ("12", "31", "32", "46", "47", "81"),
+    "83": ("04", "06", "13", "84"),
+    "84": ("04", "07", "13", "26", "30", "83"),
+    "85": ("17", "44", "49", "79"),
+    "86": ("16", "36", "37", "49", "79", "87"),
+    "87": ("16", "19", "23", "24", "36", "86"),
+    "88": ("52", "54", "55", "67", "68", "70", "90"),
+    "89": ("10", "21", "45", "58", "77"),
+    "90": ("25", "68", "70", "88"),
+    "91": ("28", "45", "77", "78", "92", "94"),
+    "92": ("75", "78", "91", "93", "94", "95"),
+    "93": ("75", "77", "92", "94", "95"),
+    "94": ("75", "77", "91", "92", "93"),
+    "95": ("27", "60", "77", "78", "92", "93"),
+}
+
 
 def department_from_postcode(post_code):
     """
diff --git a/itou/templates/search/includes/siaes_search_filters_departments.html b/itou/templates/search/includes/siaes_search_filters_departments.html
index 23d3c20014f..a6d915ff324 100644
--- a/itou/templates/search/includes/siaes_search_filters_departments.html
+++ b/itou/templates/search/includes/siaes_search_filters_departments.html
@@ -1,79 +1,78 @@
 {% load django_bootstrap5 %}
-<div id="department-fields"{% if request.htmx %} hx-swap-oob="true"{% endif %}>
-    {% if form.departments %}
-        <hr>
-        <fieldset>
-            <div class="form-group mb-0">
-                <legend class="has-collapse-caret mb-0"
-                        data-bs-toggle="collapse"
-                        href="#collapse_{{ form.departments.name }}"
-                        role="button"
-                        aria-expanded="{% if form.departments.value %}true{% else %}false{% endif %}"
-                        aria-controls="collapse_{{ form.departments.name }}">
-                    {{ form.departments.label | capfirst }}
-                </legend>
-                <div class="collapse mt-3{% if form.departments.value %} show{% endif %}" id="collapse_{{ form.departments.name }}">
-                    {{ form.departments }}
-                </div>
+
+{% if form.departments %}
+    <hr>
+    <fieldset>
+        <div class="form-group mb-0">
+            <legend class="has-collapse-caret mb-0"
+                    data-bs-toggle="collapse"
+                    href="#collapse_{{ form.departments.name }}"
+                    role="button"
+                    aria-expanded="{% if form.departments.value %}true{% else %}false{% endif %}"
+                    aria-controls="collapse_{{ form.departments.name }}">
+                {{ form.departments.label | capfirst }}
+            </legend>
+            <div class="collapse mt-3{% if form.departments.value %} show{% endif %}" id="collapse_{{ form.departments.name }}">
+                {{ form.departments }}
             </div>
-        </fieldset>
-    {% endif %}
+        </div>
+    </fieldset>
+{% endif %}
 
-    {# getattr and list still painful in Django template #}
-    {% if form.districts_13 %}
-        <hr>
-        <fieldset>
-            <div class="form-group mb-0">
-                <legend class="has-collapse-caret mb-0"
-                        data-bs-toggle="collapse"
-                        href="#collapse_{{ form.districts_13.name }}"
-                        role="button"
-                        aria-expanded="{% if form.districts_13.value %}true{% else %}false{% endif %}"
-                        aria-controls="collapse_{{ form.districts_13.name }}">
-                    {{ form.districts_13.label | capfirst }}
-                </legend>
-                <div class="collapse mt-3{% if form.districts_13.value %} show{% endif %}" id="collapse_{{ form.districts_13.name }}">
-                    {{ form.districts_13 }}
-                </div>
+{# getattr and list still painful in Django template #}
+{% if form.districts_13 %}
+    <hr>
+    <fieldset>
+        <div class="form-group mb-0">
+            <legend class="has-collapse-caret mb-0"
+                    data-bs-toggle="collapse"
+                    href="#collapse_{{ form.districts_13.name }}"
+                    role="button"
+                    aria-expanded="{% if form.districts_13.value %}true{% else %}false{% endif %}"
+                    aria-controls="collapse_{{ form.districts_13.name }}">
+                {{ form.districts_13.label | capfirst }}
+            </legend>
+            <div class="collapse mt-3{% if form.districts_13.value %} show{% endif %}" id="collapse_{{ form.districts_13.name }}">
+                {{ form.districts_13 }}
             </div>
-        </fieldset>
-    {% endif %}
+        </div>
+    </fieldset>
+{% endif %}
 
-    {% if form.districts_69 %}
-        <hr>
-        <fieldset>
-            <div class="form-group mb-0">
-                <legend class="has-collapse-caret mb-0"
-                        data-bs-toggle="collapse"
-                        href="#collapse_{{ form.districts_69.name }}"
-                        role="button"
-                        aria-expanded="{% if form.districts_69.value %}true{% else %}false{% endif %}"
-                        aria-controls="collapse_{{ form.districts_69.name }}">
-                    {{ form.districts_69.label | capfirst }}
-                </legend>
-                <div class="collapse mt-3{% if form.districts_69.value %} show{% endif %}" id="collapse_{{ form.districts_69.name }}">
-                    {{ form.districts_69 }}
-                </div>
+{% if form.districts_69 %}
+    <hr>
+    <fieldset>
+        <div class="form-group mb-0">
+            <legend class="has-collapse-caret mb-0"
+                    data-bs-toggle="collapse"
+                    href="#collapse_{{ form.districts_69.name }}"
+                    role="button"
+                    aria-expanded="{% if form.districts_69.value %}true{% else %}false{% endif %}"
+                    aria-controls="collapse_{{ form.districts_69.name }}">
+                {{ form.districts_69.label | capfirst }}
+            </legend>
+            <div class="collapse mt-3{% if form.districts_69.value %} show{% endif %}" id="collapse_{{ form.districts_69.name }}">
+                {{ form.districts_69 }}
             </div>
-        </fieldset>
-    {% endif %}
+        </div>
+    </fieldset>
+{% endif %}
 
-    {% if form.districts_75 %}
-        <hr>
-        <fieldset>
-            <div class="form-group mb-0">
-                <legend class="has-collapse-caret mb-0"
-                        data-bs-toggle="collapse"
-                        href="#collapse_{{ form.districts_75.name }}"
-                        role="button"
-                        aria-expanded="{% if form.districts_75.value %}true{% else %}false{% endif %}"
-                        aria-controls="collapse_{{ form.districts_75.name }}">
-                    {{ form.districts_75.label | capfirst }}
-                </legend>
-                <div class="collapse mt-3{% if form.districts_75.value %} show{% endif %}" id="collapse_{{ form.districts_75.name }}">
-                    {{ form.districts_75 }}
-                </div>
+{% if form.districts_75 %}
+    <hr>
+    <fieldset>
+        <div class="form-group mb-0">
+            <legend class="has-collapse-caret mb-0"
+                    data-bs-toggle="collapse"
+                    href="#collapse_{{ form.districts_75.name }}"
+                    role="button"
+                    aria-expanded="{% if form.districts_75.value %}true{% else %}false{% endif %}"
+                    aria-controls="collapse_{{ form.districts_75.name }}">
+                {{ form.districts_75.label | capfirst }}
+            </legend>
+            <div class="collapse mt-3{% if form.districts_75.value %} show{% endif %}" id="collapse_{{ form.districts_75.name }}">
+                {{ form.districts_75 }}
             </div>
-        </fieldset>
-    {% endif %}
-</div>
+        </div>
+    </fieldset>
+{% endif %}
diff --git a/itou/templates/search/includes/siaes_search_results.html b/itou/templates/search/includes/siaes_search_results.html
index 9db8049737f..396774b0e27 100644
--- a/itou/templates/search/includes/siaes_search_results.html
+++ b/itou/templates/search/includes/siaes_search_results.html
@@ -21,7 +21,6 @@
         - Les emplois de l'inclusion
     </title>
     {% include "search/includes/siaes_search_filters_company.html" %}
-    {% include "search/includes/siaes_search_filters_departments.html" %}
     {% include "search/includes/siaes_search_top.html" %}
     {% include "search/includes/siaes_search_tabs.html" %}
 {% endif %}
diff --git a/itou/templates/search/siaes_search_results.html b/itou/templates/search/siaes_search_results.html
index b08fcc2b82c..da94c54a3c9 100644
--- a/itou/templates/search/siaes_search_results.html
+++ b/itou/templates/search/siaes_search_results.html
@@ -17,13 +17,15 @@
         <div class="s-tabs-01__container container">
             <div class="s-tabs-01__row row">
                 <div class="s-tabs-01__col col-12">
-                    {% include "search/includes/siaes_search_form.html" with form=form is_home=False only %}
+                    <form>
+                        {% include "search/includes/siaes_search_form.html" with form=form is_home=False only %}
+                    </form>
                     {% include "search/includes/siaes_search_tabs.html" %}
                     <div class="tab-content">
                         {% include "search/includes/siaes_search_top.html" %}
                         <form class="d-block w-100"
                               hx-get="{% url request.resolver_match.view_name %}"
-                              hx-trigger="change delay:.5s, change from:#id_city"
+                              hx-trigger="change delay:.5s"
                               hx-indicator="#job-search-results"
                               hx-target="#job-search-results"
                               hx-swap="outerHTML"
diff --git a/itou/www/search/forms.py b/itou/www/search/forms.py
index 48a2ecbc4e4..0cd23731d48 100644
--- a/itou/www/search/forms.py
+++ b/itou/www/search/forms.py
@@ -6,7 +6,12 @@
 from django_select2.forms import Select2Widget
 
 from itou.cities.models import City
-from itou.common_apps.address.departments import DEPARTMENTS, DEPARTMENTS_WITH_DISTRICTS, format_district
+from itou.common_apps.address.departments import (
+    DEPARTMENTS,
+    DEPARTMENTS_ADJACENCY,
+    DEPARTMENTS_WITH_DISTRICTS,
+    format_district,
+)
 from itou.companies.enums import CompanyKind, ContractNature, ContractType
 from itou.jobs.models import ROME_DOMAINS
 from itou.utils.widgets import RemoteAutocompleteSelect2Widget
@@ -62,8 +67,8 @@ def clean_distance(self):
             distance = self.fields["distance"].initial
         return distance
 
-    def add_field_departements(self, departments):
-        # Build list of choices
+    def add_field_departements(self, city):
+        departments = sorted([city.department, *DEPARTMENTS_ADJACENCY[city.department]])
         choices = ((department, DEPARTMENTS[department]) for department in departments)
         self.fields["departments"] = forms.ChoiceField(
             label="Départements",
diff --git a/itou/www/search/views.py b/itou/www/search/views.py
index ff78b07ae5b..757cad9067a 100644
--- a/itou/www/search/views.py
+++ b/itou/www/search/views.py
@@ -86,7 +86,9 @@ def form_valid(self, form):
             )
         )
 
-        self.add_form_choices(form, siaes, job_descriptions)
+        form.add_field_departements(city)
+
+        self.add_form_choices(form, siaes)
 
         if kinds:
             siaes = siaes.filter(kind__in=kinds)
@@ -157,25 +159,19 @@ def form_valid(self, form):
 
 
 class EmployerSearchView(EmployerSearchBaseView):
-    def add_form_choices(self, form, siaes, _job_descriptions):
+    def add_form_choices(self, form, siaes):
         # Extract departments from results to inject them as filters
         # The DB contains around 4k SIAE (always fast in Python and no need of iterator())
-        departments = set()
         departments_districts = defaultdict(set)
         company_choices = []
         for siae in siaes:
             company_choices.append((siae.pk, siae.display_name))
-            # Extract the department of SIAE
-            if siae.department:
-                departments.add(siae.department)
-                # Extract the post_code if it's a district to use it as criteria
-                if siae.department in DEPARTMENTS_WITH_DISTRICTS:
-                    if int(siae.post_code) <= DEPARTMENTS_WITH_DISTRICTS[siae.department]["max"]:
-                        departments_districts[siae.department].add(siae.post_code)
-
-        if departments:
-            departments = sorted(departments)
-            form.add_field_departements(departments)
+            # Extract the post_code if it's a district to use it as criteria
+            if (
+                siae.department in DEPARTMENTS_WITH_DISTRICTS
+                and int(siae.post_code) <= DEPARTMENTS_WITH_DISTRICTS[siae.department]["max"]
+            ):
+                departments_districts[siae.department].add(siae.post_code)
 
         city = form.cleaned_data["city"]
         if departments_districts and city.code_insee in INSEE_CODES_WITH_DISTRICTS:
@@ -229,27 +225,16 @@ def get_results_page_and_counts(self, siaes, job_descriptions):
 class JobDescriptionSearchView(EmployerSearchBaseView):
     form_class = JobDescriptionSearchForm
 
-    def add_form_choices(self, form, _siaes, job_descriptions):
-        departments = set()
-        for job_description in job_descriptions:
-            department = None
-            if job_description.location:
-                department = job_description.location.department
-                # FIXME(vperron): on a un problème ici, c'est que les gens ne peuvent pas sélectionner
-                # un arrondissement au moment de la création d'une JobDescription: ils n'ont accès que aux "Cities"
-                # qui ne détaillent pas les arrondissements.
-                # Ce qui signifie que l'info est perdue dès le départ, à moins que l'on ne change le parcours
-                # de création des fiches de poste ou en enrichissant la table "Cities" de tous les arrondissements
-                # de Paris, Lyon et Marseille.
-                # En attendant on ne pourra pas trier par arrondissement pour ces offres.
-            elif job_description.company.department:
-                department = job_description.company.department
-            if department:
-                departments.add(department)
+    # FIXME(vperron): on a un problème ici, c'est que les gens ne peuvent pas sélectionner
+    # un arrondissement au moment de la création d'une JobDescription: ils n'ont accès que aux "Cities"
+    # qui ne détaillent pas les arrondissements.
+    # Ce qui signifie que l'info est perdue dès le départ, à moins que l'on ne change le parcours
+    # de création des fiches de poste ou en enrichissant la table "Cities" de tous les arrondissements
+    # de Paris, Lyon et Marseille.
+    # En attendant on ne pourra pas trier par arrondissement pour ces offres.
 
-        if departments:
-            departments = sorted(departments)
-            form.add_field_departements(departments)
+    def add_form_choices(self, form, siaes):
+        pass
 
     def get_results_page_and_counts(self, siaes, job_descriptions):
         job_descriptions = job_descriptions.order_by(
diff --git a/tests/www/search/tests.py b/tests/www/search/tests.py
index 20c9270bae0..47b6b2b18f7 100644
--- a/tests/www/search/tests.py
+++ b/tests/www/search/tests.py
@@ -487,7 +487,6 @@ def test_results(self):
         with self.assertNumQueries(
             BASE_NUM_QUERIES
             + 1  # select the city
-            + 1  # select job descriptions for departments filters
             + 1  # select count of job descriptions for the paginator
             + 1  # select job descriptions
             + 1  # select prefetch job applications (for the popular annotation)
@@ -550,7 +549,6 @@ def test_district(self):
         with self.assertNumQueries(
             BASE_NUM_QUERIES
             + 1  # select the city
-            + 1  # select job descriptions for departments filters
             + 1  # select count of job descriptions for the paginator
             + 1  # select job descriptions
             + 1  # select prefetch job applications (for the popular annotation)