diff --git a/.env.example b/.env.example
new file mode 100644
index 0000000..693cbf7
--- /dev/null
+++ b/.env.example
@@ -0,0 +1 @@
+GTM_CONTAINER_ID=GTM-XXXXXXX
diff --git a/.github/workflows/deploy-s3-dev.yml b/.github/workflows/deploy-s3-dev.yml
index b0af28b..2237297 100644
--- a/.github/workflows/deploy-s3-dev.yml
+++ b/.github/workflows/deploy-s3-dev.yml
@@ -32,6 +32,8 @@ jobs:
 
       - name: Build static export
         run: npm run deploy
+        env:
+          GTM_CONTAINER_ID: ${{ secrets.DEV_GTM_CONTAINER_ID }}
 
       - name: Configure AWS credentials
         uses: aws-actions/configure-aws-credentials@v4
diff --git a/.github/workflows/deploy-s3-prod.yml b/.github/workflows/deploy-s3-prod.yml
index e40df15..ac52d20 100644
--- a/.github/workflows/deploy-s3-prod.yml
+++ b/.github/workflows/deploy-s3-prod.yml
@@ -42,6 +42,8 @@ jobs:
 
       - name: Build static export
         run: npm run deploy
+        env:
+          GTM_CONTAINER_ID: ${{ secrets.GTM_CONTAINER_ID }}
 
       - name: Configure AWS credentials
         uses: aws-actions/configure-aws-credentials@v4
diff --git a/next.config.js b/next.config.js
index 1fb5231..49c7c6e 100644
--- a/next.config.js
+++ b/next.config.js
@@ -5,5 +5,8 @@ module.exports = {
       "/deploy": { page: "/deploy" }
     };
   },
-  assetPrefix: ""
+  assetPrefix: "",
+  env: {
+    GTM_CONTAINER_ID: process.env.GTM_CONTAINER_ID
+  }
 };
diff --git a/pages/_app.js b/pages/_app.js
index 66f96e7..51a6151 100644
--- a/pages/_app.js
+++ b/pages/_app.js
@@ -5,6 +5,7 @@ import Router from "next/router";
 import { Provider } from "react-redux";
 import initStore from "../src/store";
 import Meta from "../src/components/Meta";
+import MigrationBanner from "../src/components/MigrationBanner";
 
 class MyApp extends App {
   static async getInitialProps({ Component, ctx }) {
@@ -22,6 +23,7 @@ class MyApp extends App {
     return (
       <React.Fragment>
         <Meta />
+        <MigrationBanner />
         <Container>
           <Provider store={store}>
             <Component {...pageProps} />
diff --git a/pages/_document.js b/pages/_document.js
new file mode 100644
index 0000000..81097a8
--- /dev/null
+++ b/pages/_document.js
@@ -0,0 +1,37 @@
+import Document, { Html, Head, Main, NextScript } from "next/document";
+
+class MyDocument extends Document {
+  // eslint-disable-next-line class-methods-use-this
+  render() {
+    return (
+      <Html lang="en">
+        <Head>
+          {process.env.GTM_CONTAINER_ID && (
+            // eslint-disable-next-line react/no-danger
+            <script
+              dangerouslySetInnerHTML={{
+                __html: `(function(w,d,s,l,i){w[l]=w[l]||[];w[l].push({'gtm.start':new Date().getTime(),event:'gtm.js'});var f=d.getElementsByTagName(s)[0],j=d.createElement(s),dl=l!='dataLayer'?'&l='+l:'';j.async=true;j.src='https://www.googletagmanager.com/gtm.js?id='+i+dl;f.parentNode.insertBefore(j,f);})(window,document,'script','dataLayer','${process.env.GTM_CONTAINER_ID}');`
+              }}
+            />
+          )}
+        </Head>
+        <body>
+          {process.env.GTM_CONTAINER_ID && (
+            <noscript>
+              <iframe
+                src={`https://www.googletagmanager.com/ns.html?id=${process.env.GTM_CONTAINER_ID}`}
+                height="0"
+                width="0"
+                style={{ display: "none", visibility: "hidden" }}
+              />
+            </noscript>
+          )}
+          <Main />
+          <NextScript />
+        </body>
+      </Html>
+    );
+  }
+}
+
+export default MyDocument;
diff --git a/pages/index.js b/pages/index.js
index 6ac30d9..bf0e4c0 100644
--- a/pages/index.js
+++ b/pages/index.js
@@ -9,8 +9,6 @@ import PageLoader from "../src/components/UI/PageLoader";
 import { brandOrange } from "../src/styles/variables";
 
 const bannerStyle = css`
-  position: absolute;
-  top: 0;
   width: 100%;
   padding: 5px 0px;
   background: #ff9933;
diff --git a/src/components/MigrationBanner.js b/src/components/MigrationBanner.js
new file mode 100644
index 0000000..94e8881
--- /dev/null
+++ b/src/components/MigrationBanner.js
@@ -0,0 +1,35 @@
+import React from "react";
+/** @jsx jsx */
+import { css, jsx } from "@emotion/core";
+import { brandOrange } from "../styles/variables";
+
+const MIGRATION_GUIDE_URL =
+  "https://docs.opencerts.io/docs/migrations/oa_to_trustvc";
+
+const bannerStyle = css`
+  width: 100%;
+  padding: 5px 0px;
+  background: ${brandOrange};
+  text-align: center;
+  font-weight: bold;
+`;
+
+const MigrationBanner = () => (
+  <div css={css(bannerStyle)}>
+    Please note that as of 1 October 2025, OpenAttestation (OA) has been
+    deprecated. OpenCerts has since migrated to TrustVC, which uses the W3C
+    Verifiable Credentials (VC) format.
+    <br />
+    Documents previously issued in OA format remain verifiable — no action is
+    required for existing certificates. However, we recommend upgrading to the
+    W3C VC format for all new issuances.
+    <br />
+    To migrate, please refer to our{" "}
+    <a href={MIGRATION_GUIDE_URL} target="_blank" rel="noopener noreferrer">
+      migration guide
+    </a>
+    .
+  </div>
+);
+
+export default MigrationBanner;