diff --git a/core/class/declarationtva.class.php b/core/class/declarationtva.class.php
index 7e75f07..9d2d132 100644
--- a/core/class/declarationtva.class.php
+++ b/core/class/declarationtva.class.php
@@ -509,4 +509,102 @@ class DeclarationTVA
         $this->db->rollback();
         return false;
     }
+
+    /**
+     * Get account mappings for CA-3 lines
+     *
+     * @return array Account mappings
+     */
+    public function getAccountMappings()
+    {
+        $sql = "SELECT ca3_line, account_code, account_label 
+                FROM " . MAIN_DB_PREFIX . "declarationtva_account_mappings 
+                WHERE entity = " . $this->entity . " AND is_active = 1 
+                ORDER BY ca3_line, account_code";
+        
+        $result = $this->db->query($sql);
+        $mappings = array();
+        
+        if ($result) {
+            while ($obj = $this->db->fetch_object($result)) {
+                $mappings[] = array(
+                    'ca3_line' => $obj->ca3_line,
+                    'account_code' => $obj->account_code,
+                    'account_label' => $obj->account_label
+                );
+            }
+        }
+        
+        return $mappings;
+    }
+
+    /**
+     * Create CA-3 line record
+     *
+     * @param int $declaration_id Declaration ID
+     * @param string $ca3_line CA-3 line code
+     * @param string $line_label Line label
+     * @param array $amounts Amounts
+     * @return bool Success
+     */
+    public function createCA3Line($declaration_id, $ca3_line, $line_label, $amounts)
+    {
+        $sql = "INSERT INTO " . MAIN_DB_PREFIX . "declarationtva_ca3_lines 
+                (declaration_id, ca3_line, line_label, base_amount, vat_amount, total_amount, created_date) 
+                VALUES (" . $declaration_id . ", '" . $this->db->escape($ca3_line) . "', 
+                '" . $this->db->escape($line_label) . "', " . $amounts['base_amount'] . ", 
+                " . $amounts['vat_amount'] . ", " . $amounts['total_amount'] . ", NOW())";
+        
+        return $this->db->query($sql);
+    }
+
+    /**
+     * Update declaration totals
+     *
+     * @param int $declaration_id Declaration ID
+     * @param float $total_vat_collected Total VAT collected
+     * @param float $total_vat_deductible Total VAT deductible
+     * @param float $net_vat_due Net VAT due
+     * @param float $vat_credit VAT credit
+     * @return bool Success
+     */
+    public function updateDeclarationTotals($declaration_id, $total_vat_collected, $total_vat_deductible, $net_vat_due, $vat_credit)
+    {
+        $sql = "UPDATE " . MAIN_DB_PREFIX . "declarationtva_declarations 
+                SET total_vat_collected = " . $total_vat_collected . ", 
+                    total_vat_deductible = " . $total_vat_deductible . ", 
+                    net_vat_due = " . $net_vat_due . ", 
+                    vat_credit = " . $vat_credit . " 
+                WHERE rowid = " . $declaration_id;
+        
+        return $this->db->query($sql);
+    }
+
+    /**
+     * Recalculate CA-3 amounts for a declaration
+     *
+     * @param int $declaration_id Declaration ID
+     * @return bool Success
+     */
+    public function recalculateCA3Amounts($declaration_id)
+    {
+        // Get declaration info
+        $declaration = $this->getDeclarationInfo($declaration_id);
+        if (!$declaration) {
+            return false;
+        }
+        
+        // Clear existing CA-3 lines
+        $sql = "DELETE FROM " . MAIN_DB_PREFIX . "declarationtva_ca3_lines 
+                WHERE declaration_id = " . $declaration_id;
+        $this->db->query($sql);
+        
+        // Recalculate using declaration dates
+        $period = array(
+            'start_date' => $declaration['start_date'],
+            'end_date' => $declaration['end_date']
+        );
+        
+        return $this->calculateCA3Amounts($declaration_id, $period);
+    }
 }
diff --git a/declarationtva_view.php b/declarationtva_view.php
index 6b94eed..338b586 100644
--- a/declarationtva_view.php
+++ b/declarationtva_view.php
@@ -37,6 +37,18 @@ if (empty($id)) {
     accessforbidden();
 }
 
+// Handle actions
+$action = GETPOST('action', 'alpha');
+$token = GETPOST('token', 'alpha');
+
+if ($action == 'recalculate' && $token) {
+    if ($declarationtva->recalculateCA3Amounts($id)) {
+        setEventMessages($langs->trans("DeclarationRecalculated"), null, 'mesgs');
+    } else {
+        setEventMessages($langs->trans("ErrorRecalculatingDeclaration"), null, 'errors');
+    }
+}
+
 // Initialize objects
 $declarationtva = new DeclarationTVA($db, $conf->entity);
 $config = new DeclarationTVA_Config($db, $conf->entity);
@@ -155,10 +167,13 @@ print '<div class="titre">' . $langs->trans("Actions") . '</div>';
 
 print '<div class="center">';
 
+// Recalculate button (always available)
+print '<a href="' . $_SERVER['PHP_SELF'] . '?id=' . $id . '&action=recalculate&token=' . newToken() . '" class="butAction">' . $langs->trans("Recalculate") . '</a> ';
+
 if ($declarationtva->status == 'draft') {
-    print '<a href="' . $_SERVER['PHP_SELF'] . '?id=' . $id . '&action=validate" class="butAction">' . $langs->trans("Validate") . '</a>';
+    print '<a href="' . $_SERVER['PHP_SELF'] . '?id=' . $id . '&action=validate" 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>';
+    print '<a href="' . $_SERVER['PHP_SELF'] . '?id=' . $id . '&action=submit" class="butAction">' . $langs->trans("Submit") . '</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 d361d43..ed29357 100644
--- a/langs/en_US/declarationtva.lang
+++ b/langs/en_US/declarationtva.lang
@@ -426,3 +426,6 @@ CreatedDate = Created Date
 CA3Amounts = CA-3 Amounts
 CA3Line = CA-3 Line
 BackToList = Back to List
+Recalculate = Recalculate
+DeclarationRecalculated = Declaration recalculated successfully
+ErrorRecalculatingDeclaration = Error recalculating declaration
diff --git a/langs/fr_FR/declarationtva.lang b/langs/fr_FR/declarationtva.lang
index ee6c395..3232a88 100644
--- a/langs/fr_FR/declarationtva.lang
+++ b/langs/fr_FR/declarationtva.lang
@@ -415,3 +415,6 @@ CreatedDate = Date de création
 CA3Amounts = Montants CA-3
 CA3Line = Ligne CA-3
 BackToList = Retour à la liste
+Recalculate = Recalculer
+DeclarationRecalculated = Déclaration recalculée avec succès
+ErrorRecalculatingDeclaration = Erreur lors du recalcul de la déclaration