diff --git a/modules/purchase_trade/docs/business-rules.md b/modules/purchase_trade/docs/business-rules.md
index b23a8ea..f642591 100644
--- a/modules/purchase_trade/docs/business-rules.md
+++ b/modules/purchase_trade/docs/business-rules.md
@@ -542,6 +542,25 @@ Owner technique: `a completer`
 - Priorite:
   - `importante`
 
+### BR-PT-016 - Les fees `% rate` utilisent la BL Date estimee
+
+- Intent: aligner le calcul des frais financiers `% rate` entre achat et vente.
+- Description:
+  - Pour un `fee.fee` en mode `rate`, le calcul ne depend pas du
+    `payment_term`.
+  - La date de fin est toujours issue de l'onglet `Estimated date` de la ligne
+    achat ou vente:
+    - chercher `trigger = bldate`
+    - prendre `estimated_date`
+    - ajouter `fin_int_delta`
+- Resultat attendu:
+  - purchase et sale appliquent la meme formule:
+    `fee_date -> BL Date + financing delta`
+  - si aucune Estimated Date `bldate` n'est renseignee, aucun montant `% rate`
+    n'est calcule
+- Priorite:
+  - `importante`
+
 ## 4) Exemples concrets
 
 ### Exemple E1 - Augmentation simple
diff --git a/modules/purchase_trade/fee.py b/modules/purchase_trade/fee.py
index 48bed22..04ade1b 100755
--- a/modules/purchase_trade/fee.py
+++ b/modules/purchase_trade/fee.py
@@ -371,22 +371,32 @@ class Fee(ModelSQL,ModelView):
                                 )
 
                                 return round(factor * self.line.unit_price * self._get_amount_quantity() * sign,2)
-                if self.sale_line:
-                    if self.sale_line.sale.payment_term:
-                        beg_date = self.fee_date if self.fee_date else Date.today()
-                        est_date = self.sale_line.sale.payment_term.lines[0].get_date(beg_date,self.sale_line)
-                        logger.info("EST_DATE:%s",est_date)
-                        if est_date and beg_date:
-                            factor = InterestCalculator.calculate(
-                                start_date=beg_date,
-                                end_date=est_date,
-                                rate=self.price/100,
-                                rate_type='annual',
-                                convention='ACT/360',
-                                compounding='simple'
-                            )
-                            logger.info("FACTOR:%s",factor)
-                            return round(factor * self.sale_line.unit_price * self._get_amount_quantity() * sign,2)
+                if self.sale_line:
+                    if self.sale_line.estimated_date:
+                        beg_date = self.fee_date if self.fee_date else Date.today()
+                        est_lines = [
+                            dd for dd in self.sale_line.estimated_date
+                            if dd.trigger == 'bldate'
+                        ]
+                        est_line = est_lines[0] if est_lines else None
+                        if est_line and est_line.estimated_date:
+                            est_date = est_line.estimated_date + datetime.timedelta(
+                                days=est_line.fin_int_delta or 0
+                            )
+                            logger.info("EST_DATE:%s", est_date)
+                            if est_date and beg_date:
+                                factor = InterestCalculator.calculate(
+                                    start_date=beg_date,
+                                    end_date=est_date,
+                                    rate=self.price/100,
+                                    rate_type='annual',
+                                    convention='ACT/360',
+                                    compounding='simple'
+                                )
+                                logger.info("FACTOR:%s", factor)
+                                return round(
+                                    factor * self.sale_line.unit_price
+                                    * self._get_amount_quantity() * sign, 2)
 
             elif self.mode == 'perqt':
                 if self.shipment_in:
diff --git a/modules/purchase_trade/tests/test_module.py b/modules/purchase_trade/tests/test_module.py
index 777eb1d..1c893b2 100644
--- a/modules/purchase_trade/tests/test_module.py
+++ b/modules/purchase_trade/tests/test_module.py
@@ -273,6 +273,35 @@ class PurchaseTradeTestCase(ModuleTestCase):
 
             self.assertEqual(fee.get_amount(), Decimal('13.33'))
 
+    def test_sale_rate_fee_amount_uses_bl_date_estimate(self):
+        'sale rate fee amount uses BL estimated date plus financing delta'
+        Fee = Pool().get('fee.fee')
+        fee = Fee()
+        fee.mode = 'rate'
+        fee.price = Decimal('12')
+        fee.fee_date = datetime.date(2026, 4, 23)
+        fee.quantity = Decimal('10')
+        fee.unit = Mock()
+        fee.shipment_in = None
+        fee.line = None
+        fee.sale_line = Mock(
+            unit_price=Decimal('100'),
+            lots=[],
+            estimated_date=[
+                Mock(
+                    trigger='bldate',
+                    estimated_date=datetime.date(2026, 5, 23),
+                    fin_int_delta=10,
+                ),
+            ],
+        )
+
+        with patch('trytond.modules.purchase_trade.fee.Pool') as PoolMock:
+            PoolMock.return_value.get.return_value = Mock(
+                today=Mock(return_value=datetime.date(2026, 4, 23)))
+
+            self.assertEqual(fee.get_amount(), Decimal('13.33'))
+
     def test_create_pnl_price_from_line_keeps_finished_physical_sale_line(self):
         'purchase valuation keeps finished sale-side pnl on physical lots'
         Valuation = Pool().get('valuation.valuation')