diff --git a/jey_erp/custom_fields.py b/jey_erp/custom_fields.py
index 45618c4..a72d681 100644
--- a/jey_erp/custom_fields.py
+++ b/jey_erp/custom_fields.py
@@ -483,12 +483,30 @@ def create_custom_fields():
             ),
             dict(
                 fieldname='line_code',
-                label='Line Code',
+                label='YGB Line Code',
                 fieldtype='Select',
                 options='\n310\n311\n314\n316',
                 insert_after='ygb',
                 depends_on='eval:doc.purchase_type || doc.agricultural_goods'
             ),
+            # VAT offset (Əvəzləşdirmə) — can be set on submitted documents.
+            dict(
+                fieldname='vat_offset',
+                label='VAT Offset',
+                fieldtype='Check',
+                insert_after='line_code',
+                default=0,
+                allow_on_submit=1
+            ),
+            dict(
+                fieldname='vat_offset_line_code',
+                label='VAT Offset Line Code',
+                fieldtype='Select',
+                options='\n308\n314\n316',
+                insert_after='vat_offset',
+                depends_on='eval:doc.vat_offset',
+                allow_on_submit=1
+            ),
 
             # Purchase Order has no standard `remarks`, so comment 1 gets a
             # dedicated general-purpose field placed at the SAME spot as the
@@ -579,12 +597,30 @@ def create_custom_fields():
             ),
             dict(
                 fieldname='line_code',
-                label='Line Code',
+                label='YGB Line Code',
                 fieldtype='Select',
                 options='\n310\n311\n314\n316',
                 insert_after='ygb',
                 depends_on='eval:doc.purchase_type || doc.agricultural_goods'
             ),
+            # VAT offset (Əvəzləşdirmə) — can be set on submitted documents.
+            dict(
+                fieldname='vat_offset',
+                label='VAT Offset',
+                fieldtype='Check',
+                insert_after='line_code',
+                default=0,
+                allow_on_submit=1
+            ),
+            dict(
+                fieldname='vat_offset_line_code',
+                label='VAT Offset Line Code',
+                fieldtype='Select',
+                options='\n308\n314\n316',
+                insert_after='vat_offset',
+                depends_on='eval:doc.vat_offset',
+                allow_on_submit=1
+            ),
 
             # === E-TAXES INVOICE INFO (imported from e-taxes) ===
             # Series/number are parsed from the e-taxes serialNumber on import.