diff --git a/components/cover/time_based.rst b/components/cover/time_based.rst
index bbda9490b..d6ebba840 100644
--- a/components/cover/time_based.rst
+++ b/components/cover/time_based.rst
@@ -52,6 +52,9 @@ Configuration variables:
   detectors. In this configuration the ``stop_action`` is not perfomed when the open or close
   time is completed and if the cover is commanded to open or close the corresponding actions
   will be performed without checking current state. Defaults to ``False``.
+- **assumed_state** (*Optional*, boolean): Whether the true state of the cover is not known.
+  This will make the Home Assistant frontend show buttons for both OPEN and CLOSE actions, instead
+  of hiding or disabling one of them. Defaults to ``True``.
 - **id** (*Optional*, :ref:`config-id`): Manually specify the ID used for code generation.
 - All other options from :ref:`Cover <config-cover>`.