diff --git a/proto/invoice/invoice.proto b/proto/invoice/invoice.proto
index 90fc874..187e358 100644
--- a/proto/invoice/invoice.proto
+++ b/proto/invoice/invoice.proto
@@ -9,6 +9,9 @@
     // in thousands of percent points
     // (ie 23% == 23000)
     uint64 vat = 4;
+    // Denormalized fields follow.
+    uint64 total_net = 5;
+    uint64 total = 6;
 }
 
 message ContactPoint {
@@ -16,7 +19,7 @@
     string contact = 2;
 }
 
-message Invoice {
+message InvoiceData {
     repeated Item item = 1;
     repeated string invoicer_billing = 2;
     repeated ContactPoint invoicer_contact = 3;
@@ -32,8 +35,28 @@
     string unit = 13;
 }
 
+message Invoice {
+    // Original invoice parameters/data.
+    InvoiceData data = 1;
+    enum State {
+        STATE_INVALID = 0;
+        STATE_PROFORMA = 1;
+        STATE_SEALED = 2;
+    };
+    State state = 2;
+    string uid = 9;
+    // If sealed, otherwise 'proforma'.
+    string final_uid = 3;
+    int64 date = 4;
+    int64 due_date = 5;
+    // Denormalized fields follow.
+    uint64 total_net = 6;
+    uint64 total = 7;
+    string unit = 8;
+}
+
 message CreateInvoiceRequest {
-    Invoice invoice = 1;
+    InvoiceData invoice_data = 1;
 }
 
 message CreateInvoiceResponse {
@@ -47,13 +70,6 @@
 
 message GetInvoiceResponse {
     Invoice invoice = 1;
-    enum State {
-        STATE_INVALID = 0;
-        STATE_PROFORMA = 1;
-        STATE_SEALED = 2;
-    };
-    State state = 2;
-    string final_uid = 3;
 }
 
 message RenderInvoiceRequest {