HTML Code

<!DOCTYPE html>
<html lang="en">
<head>
  <meta charset="utf-8">
  <title>+3 UTC months</title>
</head>
<body>
  <h1>September + 3</h1>
  <pre id="out"></pre>
  <script>
    var start = new Date(Date.UTC(2026, 8, 10));
    var renewal = new Date(start);
    renewal.setUTCMonth(renewal.getUTCMonth() + 3);
    document.getElementById("out").textContent =
      "Start month: " + start.getUTCMonth() + "\n" +
      "Renewal month: " + renewal.getUTCMonth();
  </script>
</body>
</html>

Lines: 0 | Characters: 0

Live Preview Auto-refresh on Run

JavaScript Date setUTCMonth() — add 3 months (Try It)