diff --git a/course/flow.py b/course/flow.py
index b9ebfa4fa..da91df8c7 100644
--- a/course/flow.py
+++ b/course/flow.py
@@ -1476,6 +1476,7 @@ def view_start_flow(pctx: CoursePageContext, flow_id: str) -> http.HttpResponse:
         "grade_aggregation_strategy_descr": grade_aggregation_strategy_descr,
         "start_may_decrease_grade": start_may_decrease_grade,
         "past_sessions_and_properties": past_sessions_and_properties,
+        "course": fctx.course,
         },
         allow_instant_flow_requests=False)
 
diff --git a/course/templates/course/flow-start.html b/course/templates/course/flow-start.html
index 287317b3c..efd386d51 100644
--- a/course/templates/course/flow-start.html
+++ b/course/templates/course/flow-start.html
@@ -101,8 +101,8 @@ <h3 class="start-well-title">{% trans "Past sessions" %}</h3>
             {% endif %}
             {% if new_session_grading_rule.due %}
               <li>
-                  {% blocktrans trimmed with due=new_session_grading_rule.due %}
-                    Your session will be due on <b>{{ due }}</b>.
+                  {% blocktrans trimmed with due=new_session_grading_rule.due|eval_datespec:course  %}
+                    Your session will be due on <b>{{ due}}</b>.
                   {% endblocktrans %}
               </li>
             {% endif %}
diff --git a/course/templatetags/coursetags.py b/course/templatetags/coursetags.py
index 044666284..4993c98b0 100644
--- a/course/templatetags/coursetags.py
+++ b/course/templatetags/coursetags.py
@@ -23,10 +23,17 @@
 THE SOFTWARE.
 """
 
+from typing import TYPE_CHECKING
+
 from django.template import Library, Node, TemplateSyntaxError
 from django.utils import translation
 
 
+if TYPE_CHECKING:
+    from course.datespec import Datespec
+    from course.models import Course, Participation
+
+
 register = Library()
 
 
@@ -73,8 +80,8 @@ def do_get_current_js_lang_name(parser, token):
 
 # {{{ filter for participation.has_permission()
 
-@register.filter(name="has_permission")
-def has_permission(participation, arg):
+@register.filter
+def has_permission(participation: Participation, arg: str):
     """
     Check if a participation instance has specific permission.
     :param participation: a :class:`participation:` instance
@@ -98,7 +105,7 @@ def has_permission(participation, arg):
 # }}}
 
 
-@register.filter(name="may_set_fake_time")
+@register.filter
 def may_set_fake_time(user):
     """
     Check if a user may set fake time.
@@ -109,7 +116,7 @@ def may_set_fake_time(user):
     return msf(user)
 
 
-@register.filter(name="may_set_pretend_facility")
+@register.filter
 def may_set_pretend_facility(user):
     """
     Check if a user may set pretend_facility
@@ -120,22 +127,27 @@ def may_set_pretend_facility(user):
     return mspf(user)
 
 
-@register.filter(name="commit_message_as_html")
+@register.filter
 def commit_message_as_html(commit_sha, repo):
     from course.versioning import _get_commit_message_as_html
     return _get_commit_message_as_html(repo, commit_sha)
 
 
-@register.filter(name="get_item")
+@register.filter
 def get_item(dictionary, key):
     return dictionary.get(key, None)
 
 
-@register.filter(name="get_item_or_key")
+@register.filter
 def get_item_or_key(dictionary, key):
     return dictionary.get(key, key)
 
 
-@register.filter(name="startswith")
-def startswith(s, arg):
+@register.filter
+def startswith(s: str, arg: str):
     return s.startswith(arg)
+
+
+@register.filter
+def eval_datespec(dspec: Datespec, course: Course):
+    return dspec.eval(course)