diff --git a/sql/v01/13.create.payment.sql b/sql/v01/13.create.payment.sql
index dc1b9c4..bbb7c1e 100644
--- a/sql/v01/13.create.payment.sql
+++ b/sql/v01/13.create.payment.sql
@@ -158,8 +158,8 @@ CREATE TABLE credit (
     net_amount      INTEGER NOT NULL,
     prev_net_amount INTEGER,
     vat             REAL    NOT NULL,
-    vat_amount      INTEGER NOT NULL GENERATED ALWAYS AS (ROUND((net_amount - COALESCE(prev_net_amount, 0)) * vat)) VIRTUAL,
-    gross_amount    INTEGER NOT NULL GENERATED ALWAYS AS (net_amount - COALESCE(prev_net_amount, 0) + vat_amount) VIRTUAL,
+    vat_amount      INTEGER NOT NULL GENERATED ALWAYS AS (ROUND((net_amount - COALESCE(prev_net_amount, 0)) * vat)) STORED,
+    gross_amount    INTEGER NOT NULL GENERATED ALWAYS AS (net_amount - COALESCE(prev_net_amount, 0) + vat_amount) STORED,
     modifiers       INTEGER,
     prev_modifiers  INTEGER,
     amount          INTEGER NOT NULL GENERATED ALWAYS AS (gross_amount + COALESCE(modifiers, 0) - COALESCE(prev_modifiers, 0)) STORED,