diff --git a/modules/customer-invoices/src/web/proformas/update/adapters/map-proforma-to-proforma-update-form.adapter.ts b/modules/customer-invoices/src/web/proformas/update/adapters/map-proforma-to-proforma-update-form.adapter.ts
index 9016ab56..d23fcbb4 100644
--- a/modules/customer-invoices/src/web/proformas/update/adapters/map-proforma-to-proforma-update-form.adapter.ts
+++ b/modules/customer-invoices/src/web/proformas/update/adapters/map-proforma-to-proforma-update-form.adapter.ts
@@ -21,6 +21,8 @@ export const mapProformaToProformaUpdateForm = (proforma: Proforma): ProformaUpd
   const fiscalDefaults = resolveFiscalDefaults(proforma, proformaDefaults);
 
   return {
+    invoiceNumber: proforma.invoiceNumber,
+
     series: proforma.series ?? proformaDefaults.series,
 
     invoiceDate: proforma.invoiceDate ?? proformaDefaults.invoiceDate,
diff --git a/modules/customer-invoices/src/web/proformas/update/entities/proforma-update-form.entity.ts b/modules/customer-invoices/src/web/proformas/update/entities/proforma-update-form.entity.ts
index 0b95121d..e295375b 100644
--- a/modules/customer-invoices/src/web/proformas/update/entities/proforma-update-form.entity.ts
+++ b/modules/customer-invoices/src/web/proformas/update/entities/proforma-update-form.entity.ts
@@ -18,6 +18,8 @@ import type { ProformaItemUpdateForm } from "./proforma-item-update-form.entity"
 export type ProformaTaxMode = "single" | "perLine";
 
 export interface ProformaUpdateForm {
+  invoiceNumber: string;
+
   series: string;
 
   invoiceDate: string;
diff --git a/modules/customer-invoices/src/web/proformas/update/ui/editors/proforma-update-header-editor.tsx b/modules/customer-invoices/src/web/proformas/update/ui/editors/proforma-update-header-editor.tsx
index 262a2d39..0fdf6ee8 100644
--- a/modules/customer-invoices/src/web/proformas/update/ui/editors/proforma-update-header-editor.tsx
+++ b/modules/customer-invoices/src/web/proformas/update/ui/editors/proforma-update-header-editor.tsx
@@ -38,7 +38,7 @@ export const ProformaUpdateHeaderEditor = ({
       <FormSectionGrid>
         <TextField
           className="md:col-span-2"
-          disabled={disabled}
+          disabled={true}
           label={t("form_fields.proformas.invoice_number.label")}
           maxLength={16}
           name="invoiceNumber"
diff --git a/packages/rdx-ui/src/components/form/text-field.tsx b/packages/rdx-ui/src/components/form/text-field.tsx
index 44889398..ed7f1675 100644
--- a/packages/rdx-ui/src/components/form/text-field.tsx
+++ b/packages/rdx-ui/src/components/form/text-field.tsx
@@ -16,14 +16,6 @@ import type { NativeInputProps } from "./types.ts";
 
 export type ProformaFieldSpan = "xs" | "sm" | "md" | "lg" | "full";
 
-const fieldSpanClasses: Record<ProformaFieldSpan, string> = {
-  xs: "md:col-span-2",
-  sm: "md:col-span-3",
-  md: "md:col-span-4",
-  lg: "md:col-span-6",
-  full: "md:col-span-12",
-};
-
 type TextFieldProps<TFormValues extends FieldValues> = Omit<NativeInputProps, "name"> & {
   name: FieldPath<TFormValues>;