diff --git a/core/class/declarationtva.class.php b/core/class/declarationtva.class.php
index d773891..e2b28df 100644
--- a/core/class/declarationtva.class.php
+++ b/core/class/declarationtva.class.php
@@ -1035,6 +1035,50 @@ class DeclarationTVA
         return true;
     }
     
+    /**
+     * Unvalidate a declaration (for testing purposes)
+     *
+     * @param int $declaration_id Declaration ID
+     * @return bool Success
+     */
+    public function unvalidateDeclaration($declaration_id)
+    {
+        // Check if the validated_date and validated_by columns exist
+        $sql_check_columns = "SHOW COLUMNS FROM " . MAIN_DB_PREFIX . "declarationtva_declarations LIKE 'validated_date'";
+        $result_check = $this->db->query($sql_check_columns);
+        $has_validated_columns = ($result_check && $this->db->num_rows($result_check) > 0);
+        
+        if ($has_validated_columns) {
+            // Use the enhanced version with validated_date and validated_by
+            $sql = "UPDATE " . MAIN_DB_PREFIX . "declarationtva_declarations 
+                    SET status = 'draft', 
+                        validated_date = NULL,
+                        validated_by = NULL
+                    WHERE rowid = " . (int)$declaration_id . " 
+                    AND entity = " . $this->entity;
+        } else {
+            // Use the basic version without the additional columns
+            $sql = "UPDATE " . MAIN_DB_PREFIX . "declarationtva_declarations 
+                    SET status = 'draft'
+                    WHERE rowid = " . (int)$declaration_id . " 
+                    AND entity = " . $this->entity;
+        }
+        
+        $result = $this->db->query($sql);
+        if (!$result) {
+            $this->error = "Database error updating declaration: " . $this->db->lasterror();
+            return false;
+        }
+        
+        // Check if the update actually affected any rows
+        if ($this->db->affected_rows($result) == 0) {
+            $this->error = "No declaration found with ID " . $declaration_id . " or insufficient permissions";
+            return false;
+        }
+        
+        return true;
+    }
+    
     /**
      * Save validated PDF to Dolibarr documents
      *
diff --git a/declarationtva_view.php b/declarationtva_view.php
index 5504541..f390ac8 100644
--- a/declarationtva_view.php
+++ b/declarationtva_view.php
@@ -122,6 +122,15 @@ if ($action == 'validate' && $token) {
     }
 }
 
+if ($action == 'unvalidate' && $token) {
+    // Unvalidate the declaration (for testing purposes)
+    if ($declarationtva->unvalidateDeclaration($id)) {
+        setEventMessages($langs->trans("DeclarationUnvalidated"), null, 'mesgs');
+    } else {
+        setEventMessages($langs->trans("ErrorUnvalidatingDeclaration") . ": " . $declarationtva->error, null, 'errors');
+    }
+}
+
 // Fetch declaration
 if ($declarationtva->fetch($id) < 0) {
     setEventMessages($langs->trans("DeclarationNotFound"), null, 'errors');
@@ -447,6 +456,8 @@ if ($declarationtva->status == 'draft') {
     print '<a href="#" onclick="confirmValidation(' . $id . '); return false;" class="butAction">' . $langs->trans("Validate") . '</a> ';
 } elseif ($declarationtva->status == 'validated') {
     print '<a href="' . $_SERVER['PHP_SELF'] . '?id=' . $id . '&action=submit" class="butAction">' . $langs->trans("Submit") . '</a> ';
+    // Add unvalidate button for testing
+    print '<a href="' . $_SERVER['PHP_SELF'] . '?id=' . $id . '&action=unvalidate&token=' . newToken() . '" class="butAction" style="background-color: #dc3545;" onclick="return confirm(\'' . $langs->trans("ConfirmUnvalidate") . '\')">' . $langs->trans("Unvalidate") . '</a> ';
 }
 
 print '<a href="declarationtvaindex.php" class="butAction">' . $langs->trans("BackToList") . '</a>';
diff --git a/langs/en_US/declarationtva.lang b/langs/en_US/declarationtva.lang
index d3a1df6..ed7191b 100644
--- a/langs/en_US/declarationtva.lang
+++ b/langs/en_US/declarationtva.lang
@@ -501,6 +501,10 @@ YesValidate = Yes, validate
 Cancel = Cancel
 DeclarationValidated = Declaration validated successfully
 ErrorValidatingDeclaration = Error validating declaration
+DeclarationUnvalidated = Declaration reverted to draft
+ErrorUnvalidatingDeclaration = Error reverting to draft
+Unvalidate = Revert to Draft
+ConfirmUnvalidate = Are you sure you want to revert this declaration to draft status?
 
 # Document and status icons
 Document = Document
diff --git a/langs/fr_FR/declarationtva.lang b/langs/fr_FR/declarationtva.lang
index f1c519b..44c4be9 100644
--- a/langs/fr_FR/declarationtva.lang
+++ b/langs/fr_FR/declarationtva.lang
@@ -473,6 +473,10 @@ YesValidate = Oui, valider
 Cancel = Annuler
 DeclarationValidated = Déclaration validée avec succès
 ErrorValidatingDeclaration = Erreur lors de la validation de la déclaration
+DeclarationUnvalidated = Déclaration remise en brouillon
+ErrorUnvalidatingDeclaration = Erreur lors de la remise en brouillon
+Unvalidate = Remettre en brouillon
+ConfirmUnvalidate = Êtes-vous sûr de vouloir remettre cette déclaration en brouillon ?
 
 # Document and status icons
 Document = Document