diff --git a/admin/setup_mvp.php b/admin/setup_mvp.php
index 9342dbd..c9ae18d 100644
--- a/admin/setup_mvp.php
+++ b/admin/setup_mvp.php
@@ -1,7 +1,7 @@
 <?php
 /**
  * MVP Setup page for DeclarationTVA module
- * Simplified configuration for Phase 1
+ * Complete CA-3 configuration with all sections and headers
  */
 
 // Load Dolibarr environment
@@ -34,9 +34,9 @@ $config = new DeclarationTVA_Config($db, $conf->entity);
 // Handle form submission
 $action = GETPOST('action', 'alpha');
 if ($action == 'update_mappings') {
-    $ca3_lines = array('A1', 'A2', 'B1', 'B2', 'B3', 'B4', '17', '20', '21', '22', '28', '29');
+    $ca3_definitions = $config->getCA3LineDefinitions();
     
-    foreach ($ca3_lines as $line) {
+    foreach ($ca3_definitions as $line => $definition) {
         $account_code = GETPOST('account_code_' . $line, 'alpha');
         $account_label = GETPOST('account_label_' . $line, 'alpha');
         $vat_rate = GETPOST('vat_rate_' . $line, 'alpha');
@@ -60,6 +60,7 @@ foreach ($mappings as $mapping) {
 $accounts = $config->getAccountingAccounts();
 $vat_rates = $config->getVATRates();
 $ca3_definitions = $config->getCA3LineDefinitions();
+$section_headers = $config->getCA3SectionHeaders();
 
 // Page title
 $title = $langs->trans("DeclarationTVASetup");
@@ -75,43 +76,65 @@ print '<input type="hidden" name="action" value="update_mappings">';
 print '<div class="fiche">';
 print '<div class="titre">' . $langs->trans("DeclarationTVAPCGMapping") . '</div>';
 
-print '<table class="noborder centpercent">';
-print '<tr class="liste_titre">';
-print '<th>' . $langs->trans("CA3Line") . '</th>';
-print '<th>' . $langs->trans("LineLabel") . '</th>';
-print '<th>' . $langs->trans("AccountCode") . '</th>';
-print '<th>' . $langs->trans("AccountLabel") . '</th>';
-print '<th>' . $langs->trans("VATRate") . '</th>';
-print '</tr>';
-
+// Group CA-3 lines by section
+$lines_by_section = array();
 foreach ($ca3_definitions as $line => $definition) {
-    $mapping = isset($account_mappings[$line]) ? $account_mappings[$line] : array();
-    
-    print '<tr>';
-    print '<td><strong>' . $line . '</strong></td>';
-    print '<td>' . $definition['label'] . '</td>';
-    print '<td>';
-    print '<select name="account_code_' . $line . '" class="flat">';
-    print '<option value="">' . $langs->trans("SelectAccount") . '</option>';
-    foreach ($accounts as $account) {
-        $selected = (isset($mapping['account_code']) && $mapping['account_code'] == $account['account_number']) ? 'selected' : '';
-        print '<option value="' . $account['account_number'] . '" ' . $selected . '>' . $account['account_number'] . ' - ' . $account['label'] . '</option>';
+    $section = $definition['section'];
+    if (!isset($lines_by_section[$section])) {
+        $lines_by_section[$section] = array();
     }
-    print '</select>';
-    print '</td>';
-    print '<td><input type="text" name="account_label_' . $line . '" value="' . (isset($mapping['account_label']) ? $mapping['account_label'] : '') . '" class="flat" size="30"></td>';
-    print '<td>';
-    print '<select name="vat_rate_' . $line . '" class="flat">';
-    foreach ($vat_rates as $rate => $label) {
-        $selected = (isset($mapping['vat_rate']) && $mapping['vat_rate'] == $rate) ? 'selected' : '';
-        print '<option value="' . $rate . '" ' . $selected . '>' . $label . '</option>';
-    }
-    print '</select>';
-    print '</td>';
-    print '</tr>';
+    $lines_by_section[$section][$line] = $definition;
 }
 
-print '</table>';
+// Print each section
+foreach ($lines_by_section as $section_code => $lines) {
+    $section_info = $section_headers[$section_code];
+    
+    // Section header
+    print '<div class="titre">' . $section_info['title'] . '</div>';
+    print '<div class="info">' . $section_info['description'] . '</div>';
+    
+    print '<table class="noborder centpercent">';
+    print '<tr class="liste_titre">';
+    print '<th>' . $langs->trans("CA3Line") . '</th>';
+    print '<th>' . $langs->trans("LineLabel") . '</th>';
+    print '<th>' . $langs->trans("AccountCode") . '</th>';
+    print '<th>' . $langs->trans("AccountLabel") . '</th>';
+    print '<th>' . $langs->trans("VATRate") . '</th>';
+    print '<th>' . $langs->trans("Type") . '</th>';
+    print '</tr>';
+
+    foreach ($lines as $line => $definition) {
+        $mapping = isset($account_mappings[$line]) ? $account_mappings[$line] : array();
+        
+        print '<tr>';
+        print '<td><strong>' . $line . '</strong></td>';
+        print '<td>' . $definition['label'] . '</td>';
+        print '<td>';
+        print '<select name="account_code_' . $line . '" class="flat">';
+        print '<option value="">' . $langs->trans("SelectAccount") . '</option>';
+        foreach ($accounts as $account) {
+            $selected = (isset($mapping['account_code']) && $mapping['account_code'] == $account['account_number']) ? 'selected' : '';
+            print '<option value="' . $account['account_number'] . '" ' . $selected . '>' . $account['account_number'] . ' - ' . $account['label'] . '</option>';
+        }
+        print '</select>';
+        print '</td>';
+        print '<td><input type="text" name="account_label_' . $line . '" value="' . (isset($mapping['account_label']) ? $mapping['account_label'] : '') . '" class="flat" size="30"></td>';
+        print '<td>';
+        print '<select name="vat_rate_' . $line . '" class="flat">';
+        foreach ($vat_rates as $rate => $label) {
+            $selected = (isset($mapping['vat_rate']) && $mapping['vat_rate'] == $rate) ? 'selected' : '';
+            print '<option value="' . $rate . '" ' . $selected . '>' . $label . '</option>';
+        }
+        print '</select>';
+        print '</td>';
+        print '<td><span class="badge badge-' . ($definition['type'] == 'base' ? 'info' : 'success') . '">' . ucfirst($definition['type']) . '</span></td>';
+        print '</tr>';
+    }
+
+    print '</table>';
+    print '<br>';
+}
 
 print '<div class="titre">' . $langs->trans("Actions") . '</div>';
 print '<input type="submit" class="button" value="' . $langs->trans("UpdateConfiguration") . '">';
@@ -119,36 +142,56 @@ print '</div>';
 
 print '</form>';
 
-// Print current configuration
+// Print current configuration summary
 print '<div class="fiche">';
 print '<div class="titre">' . $langs->trans("CurrentConfiguration") . '</div>';
 
 if (empty($mappings)) {
     print '<div class="info">' . $langs->trans("NoConfigurationFound") . '</div>';
 } else {
-    print '<table class="noborder centpercent">';
-    print '<tr class="liste_titre">';
-    print '<th>' . $langs->trans("CA3Line") . '</th>';
-    print '<th>' . $langs->trans("AccountCode") . '</th>';
-    print '<th>' . $langs->trans("AccountLabel") . '</th>';
-    print '<th>' . $langs->trans("VATRate") . '</th>';
-    print '<th>' . $langs->trans("Status") . '</th>';
-    print '</tr>';
-
+    // Group by section for display
+    $mappings_by_section = array();
     foreach ($mappings as $mapping) {
-        print '<tr>';
-        print '<td><strong>' . $mapping['ca3_line'] . '</strong></td>';
-        print '<td>' . $mapping['account_code'] . '</td>';
-        print '<td>' . $mapping['account_label'] . '</td>';
-        print '<td>' . $mapping['vat_rate'] . '%</td>';
-        print '<td>' . ($mapping['is_active'] ? $langs->trans("Active") : $langs->trans("Inactive")) . '</td>';
-        print '</tr>';
+        $line = $mapping['ca3_line'];
+        if (isset($ca3_definitions[$line])) {
+            $section = $ca3_definitions[$line]['section'];
+            if (!isset($mappings_by_section[$section])) {
+                $mappings_by_section[$section] = array();
+            }
+            $mappings_by_section[$section][] = $mapping;
+        }
+    }
+    
+    foreach ($mappings_by_section as $section_code => $section_mappings) {
+        $section_info = $section_headers[$section_code];
+        
+        print '<div class="titre">' . $section_info['title'] . '</div>';
+        
+        print '<table class="noborder centpercent">';
+        print '<tr class="liste_titre">';
+        print '<th>' . $langs->trans("CA3Line") . '</th>';
+        print '<th>' . $langs->trans("AccountCode") . '</th>';
+        print '<th>' . $langs->trans("AccountLabel") . '</th>';
+        print '<th>' . $langs->trans("VATRate") . '</th>';
+        print '<th>' . $langs->trans("Status") . '</th>';
+        print '</tr>';
+
+        foreach ($section_mappings as $mapping) {
+            print '<tr>';
+            print '<td><strong>' . $mapping['ca3_line'] . '</strong></td>';
+            print '<td>' . $mapping['account_code'] . '</td>';
+            print '<td>' . $mapping['account_label'] . '</td>';
+            print '<td>' . $mapping['vat_rate'] . '%</td>';
+            print '<td>' . ($mapping['is_active'] ? $langs->trans("Active") : $langs->trans("Inactive")) . '</td>';
+            print '</tr>';
+        }
+        print '</table>';
+        print '<br>';
     }
-    print '</table>';
 }
 
 print '</div>';
 
 // Print footer
 llxFooter();
-?>
+?>
\ No newline at end of file
diff --git a/core/class/declarationtva_config.class.php b/core/class/declarationtva_config.class.php
index e748a4a..e0836dd 100644
--- a/core/class/declarationtva_config.class.php
+++ b/core/class/declarationtva_config.class.php
@@ -182,18 +182,56 @@ class DeclarationTVA_Config
     public function getCA3LineDefinitions()
     {
         return array(
-            'A1' => array('label' => 'Montant hors TVA des opérations imposables', 'type' => 'base'),
-            'A2' => array('label' => 'Opérations imposables mais ne relevant pas du CA courant', 'type' => 'base'),
-            'B1' => array('label' => 'Répartition 20% (base + taxe)', 'type' => 'vat'),
-            'B2' => array('label' => 'Répartition 10% (base + taxe)', 'type' => 'vat'),
-            'B3' => array('label' => 'Répartition 5,5% (base + taxe)', 'type' => 'vat'),
-            'B4' => array('label' => 'Répartition 2,1% (base + taxe)', 'type' => 'vat'),
-            '17' => array('label' => 'TVA due au titre des acquisitions intracommunautaires', 'type' => 'vat'),
-            '20' => array('label' => 'TVA déductible sur immobilisations', 'type' => 'vat'),
-            '21' => array('label' => 'TVA déductible sur autres biens et services', 'type' => 'vat'),
-            '22' => array('label' => 'Crédit de TVA reportable', 'type' => 'vat'),
-            '28' => array('label' => 'TVA nette à payer', 'type' => 'vat'),
-            '29' => array('label' => 'Crédit de TVA à reporter ou remboursement', 'type' => 'vat')
+            // A. Opérations imposables (Taxable Operations)
+            'A1' => array('label' => 'Montant hors TVA des opérations imposables', 'type' => 'base', 'section' => 'A'),
+            'A2' => array('label' => 'Opérations imposables mais ne relevant pas du CA courant', 'type' => 'base', 'section' => 'A'),
+            'B1' => array('label' => 'Répartition 20% (base + taxe)', 'type' => 'vat', 'section' => 'A'),
+            'B2' => array('label' => 'Répartition 10% (base + taxe)', 'type' => 'vat', 'section' => 'A'),
+            'B3' => array('label' => 'Répartition 5,5% (base + taxe)', 'type' => 'vat', 'section' => 'A'),
+            'B4' => array('label' => 'Répartition 2,1% (base + taxe)', 'type' => 'vat', 'section' => 'A'),
+            
+            // A. Opérations intracommunautaires (Intra-EU Operations)
+            '05' => array('label' => 'Livraisons intracommunautaires (B2B)', 'type' => 'base', 'section' => 'A'),
+            '06' => array('label' => 'Prestations intracommunautaires (B2B)', 'type' => 'base', 'section' => 'A'),
+            
+            // B. TVA due (VAT Due)
+            '17' => array('label' => 'TVA due au titre des acquisitions intracommunautaires', 'type' => 'vat', 'section' => 'B'),
+            
+            // C. TVA déductible (Deductible VAT)
+            '20' => array('label' => 'TVA déductible sur immobilisations', 'type' => 'vat', 'section' => 'C'),
+            '21' => array('label' => 'TVA déductible sur autres biens et services', 'type' => 'vat', 'section' => 'C'),
+            
+            // D. Résultat (Result)
+            '22' => array('label' => 'Crédit de TVA reportable', 'type' => 'vat', 'section' => 'D'),
+            '28' => array('label' => 'TVA nette à payer', 'type' => 'vat', 'section' => 'D'),
+            '29' => array('label' => 'Crédit de TVA à reporter ou remboursement', 'type' => 'vat', 'section' => 'D')
+        );
+    }
+
+    /**
+     * Get CA-3 section headers
+     *
+     * @return array Section headers
+     */
+    public function getCA3SectionHeaders()
+    {
+        return array(
+            'A' => array(
+                'title' => 'A. Opérations imposables (Taxable Operations)',
+                'description' => 'Base amounts and VAT for domestic taxable operations'
+            ),
+            'B' => array(
+                'title' => 'B. TVA due (VAT Due)',
+                'description' => 'VAT amounts due from intra-EU acquisitions and other sources'
+            ),
+            'C' => array(
+                'title' => 'C. TVA déductible (Deductible VAT)',
+                'description' => 'VAT amounts that can be deducted from purchases and expenses'
+            ),
+            'D' => array(
+                'title' => 'D. Résultat (Result)',
+                'description' => 'Final calculation: net VAT to pay or credit to carry forward'
+            )
         );
     }
 
diff --git a/langs/en_US/declarationtva.lang b/langs/en_US/declarationtva.lang
index 26441c2..d040b28 100644
--- a/langs/en_US/declarationtva.lang
+++ b/langs/en_US/declarationtva.lang
@@ -330,3 +330,30 @@ DeclarationTVASupplierAnalysis = Supplier Analysis
 DeclarationTVAGeographicAnalysis = Geographic Analysis
 DeclarationTVAProductAnalysis = Product Analysis
 DeclarationTVASeasonalAnalysis = Seasonal Analysis
+
+# CA-3 Section Headers
+CA3SectionA = Taxable Operations
+CA3SectionB = VAT Due
+CA3SectionC = Deductible VAT
+CA3SectionD = Result
+
+# CA-3 Line Labels
+CA3LineA1 = Base amount of taxable operations
+CA3LineA2 = Taxable operations not part of current revenue
+CA3LineB1 = 20% VAT operations
+CA3LineB2 = 10% VAT operations
+CA3LineB3 = 5.5% VAT operations
+CA3LineB4 = 2.1% VAT operations
+CA3Line05 = Intra-EU goods deliveries (B2B)
+CA3Line06 = Intra-EU services (B2B)
+CA3Line17 = VAT due on intra-EU acquisitions
+CA3Line20 = Deductible VAT on fixed assets
+CA3Line21 = Deductible VAT on other goods and services
+CA3Line22 = VAT credit to carry forward
+CA3Line28 = Net VAT to pay
+CA3Line29 = VAT credit to carry forward or refund
+
+# Form Labels
+Type = Type
+Base = Base
+VAT = VAT
diff --git a/langs/fr_FR/declarationtva.lang b/langs/fr_FR/declarationtva.lang
index 0269b35..d9f30db 100644
--- a/langs/fr_FR/declarationtva.lang
+++ b/langs/fr_FR/declarationtva.lang
@@ -319,3 +319,30 @@ DeclarationTVASupplierAnalysis = Analyse fournisseurs
 DeclarationTVAGeographicAnalysis = Analyse géographique
 DeclarationTVAProductAnalysis = Analyse produits
 DeclarationTVASeasonalAnalysis = Analyse saisonnière
+
+# En-têtes des sections CA-3
+CA3SectionA = Opérations imposables
+CA3SectionB = TVA due
+CA3SectionC = TVA déductible
+CA3SectionD = Résultat
+
+# Labels des lignes CA-3
+CA3LineA1 = Montant hors TVA des opérations imposables
+CA3LineA2 = Opérations imposables mais ne relevant pas du CA courant
+CA3LineB1 = Opérations à 20%
+CA3LineB2 = Opérations à 10%
+CA3LineB3 = Opérations à 5,5%
+CA3LineB4 = Opérations à 2,1%
+CA3Line05 = Livraisons intracommunautaires (B2B)
+CA3Line06 = Prestations intracommunautaires (B2B)
+CA3Line17 = TVA due au titre des acquisitions intracommunautaires
+CA3Line20 = TVA déductible sur immobilisations
+CA3Line21 = TVA déductible sur autres biens et services
+CA3Line22 = Crédit de TVA reportable
+CA3Line28 = TVA nette à payer
+CA3Line29 = Crédit de TVA à reporter ou remboursement
+
+# Labels de formulaire
+Type = Type
+Base = Base
+VAT = TVA