diff --git a/admin/setup_mvp.php b/admin/setup_mvp.php
index 3b495e0..52484c8 100644
--- a/admin/setup_mvp.php
+++ b/admin/setup_mvp.php
@@ -154,6 +154,12 @@ foreach ($lines_by_section as $section_code => $lines) {
         print '<div class="info"><strong>Référence:</strong> ' . $section_info['notice'] . '</div>';
     }
     
+    // Skip D-section lines (25, 26, 28, 29) as they are calculated
+    if ($section_code == 'D') {
+        print '<div class="info"><strong>Note:</strong> Les lignes de la section D sont calculées automatiquement à partir des autres sections.</div>';
+        continue;
+    }
+    
     print '<table class="noborder centpercent">';
     print '<tr class="liste_titre">';
     print '<th>' . $langs->trans("CA3Line") . '</th>';
diff --git a/core/class/declarationtva.class.php b/core/class/declarationtva.class.php
index 957745f..59dca09 100644
--- a/core/class/declarationtva.class.php
+++ b/core/class/declarationtva.class.php
@@ -276,6 +276,9 @@ class DeclarationTVA
             }
         }
 
+        // Calculate D-section result lines (25, 26, 28, 29)
+        $this->calculateDSectionLines($declaration_id, $total_vat_collected, $total_vat_deductible);
+
         // Calculate net amounts
         $net_vat_due = $total_vat_collected - $total_vat_deductible;
         $vat_credit = $net_vat_due < 0 ? abs($net_vat_due) : 0;
@@ -287,6 +290,69 @@ class DeclarationTVA
         return true;
     }
 
+    /**
+     * Calculate D-section result lines (25, 26, 28, 29)
+     *
+     * @param int $declaration_id Declaration ID
+     * @param float $total_vat_collected Total VAT collected
+     * @param float $total_vat_deductible Total VAT deductible
+     * @return bool Success
+     */
+    private function calculateDSectionLines($declaration_id, $total_vat_collected, $total_vat_deductible)
+    {
+        // Line 25: TVA brute due (Total VAT due)
+        $line_25_amount = $total_vat_collected;
+        $this->createCA3Line($declaration_id, '25', 'Calculated from sections A and B', array(
+            'base_amount' => 0,
+            'vat_amount' => $line_25_amount,
+            'total_amount' => $line_25_amount
+        ));
+
+        // Line 26: TVA déductible totale (Total deductible VAT)
+        $line_26_amount = $total_vat_deductible;
+        $this->createCA3Line($declaration_id, '26', 'Calculated from section C', array(
+            'base_amount' => 0,
+            'vat_amount' => $line_26_amount,
+            'total_amount' => $line_26_amount
+        ));
+
+        // Calculate net VAT due
+        $net_vat_due = $total_vat_collected - $total_vat_deductible;
+
+        // Line 28: TVA nette due (Net VAT due) - if positive
+        if ($net_vat_due > 0) {
+            $this->createCA3Line($declaration_id, '28', 'Calculated: 25 - 26', array(
+                'base_amount' => 0,
+                'vat_amount' => $net_vat_due,
+                'total_amount' => $net_vat_due
+            ));
+        } else {
+            $this->createCA3Line($declaration_id, '28', 'Calculated: 25 - 26', array(
+                'base_amount' => 0,
+                'vat_amount' => 0,
+                'total_amount' => 0
+            ));
+        }
+
+        // Line 29: Crédit de TVA (VAT Credit) - if negative
+        if ($net_vat_due < 0) {
+            $vat_credit = abs($net_vat_due);
+            $this->createCA3Line($declaration_id, '29', 'Calculated: 26 - 25', array(
+                'base_amount' => 0,
+                'vat_amount' => $vat_credit,
+                'total_amount' => $vat_credit
+            ));
+        } else {
+            $this->createCA3Line($declaration_id, '29', 'Calculated: 26 - 25', array(
+                'base_amount' => 0,
+                'vat_amount' => 0,
+                'total_amount' => 0
+            ));
+        }
+
+        return true;
+    }
+
     /**
      * Get account amounts for a period
      *