diff --git a/odoo/upsell.html b/odoo/upsell.html
index e7eb6c4..4ce3b23 100644
--- a/odoo/upsell.html
+++ b/odoo/upsell.html
@@ -342,6 +342,41 @@
                 powerhouse: 5,
             };
 
+            // ── UTM tracking (source / medium / campaign) ─────────────────────────────
+            const UTM_KEYS = ["source", "medium", "campaign"];
+
+            function getCookie(name) {
+                const match = document.cookie.match(new RegExp("(^| )" + name + "=([^;]+)"));
+                return match ? decodeURIComponent(match[2]) : null;
+            }
+
+            function setCookie(name, value, days) {
+                const date = new Date();
+                date.setTime(date.getTime() + days * 24 * 60 * 60 * 1000);
+                document.cookie =
+                    name + "=" + encodeURIComponent(value) +
+                    "; expires=" + date.toUTCString() +
+                    "; path=/; SameSite=Lax";
+            }
+
+            UTM_KEYS.forEach(function (key) {
+                const val = params.get("utm_" + key);
+                if (val) setCookie("utm_" + key, val, 90);
+            });
+
+            function appendUTM(form) {
+                UTM_KEYS.forEach(function (key) {
+                    const val = getCookie("utm_" + key);
+                    if (val) {
+                        const input = document.createElement("input");
+                        input.type = "hidden";
+                        input.name = "utm_" + key;
+                        input.value = val;
+                        form.appendChild(input);
+                    }
+                });
+            }
+
             // ── Buy handler ───────────────────────────────────────────────────────────
             function buyProduct(productId) {
                 if (!uuid) {
@@ -369,6 +404,7 @@
                 clear.name = "clear";
                 clear.value = "1";
                 form.appendChild(clear);
+                appendUTM(form);
                 document.body.appendChild(form);
                 form.submit();
                 document.body.removeChild(form);
diff --git a/script.js b/script.js
index a97c449..049b48a 100644
--- a/script.js
+++ b/script.js
@@ -57,7 +57,33 @@ var si = 0,
         return data;
     }
 
-    window.UTM = { parse: parseUTM, getStored: getStoredUTM, inject: injectUTM };
+    function appendToForm(form) {
+        var stored = getStoredUTM();
+        var keys = ['source', 'medium', 'campaign'];
+        for (var i = 0; i < keys.length; i++) {
+            if (stored[keys[i]]) {
+                var input = document.createElement('input');
+                input.type = 'hidden';
+                input.name = 'utm_' + keys[i];
+                input.value = stored[keys[i]];
+                form.appendChild(input);
+            }
+        }
+    }
+
+    function toQuery() {
+        var stored = getStoredUTM();
+        var parts = [];
+        var keys = ['source', 'medium', 'campaign'];
+        for (var i = 0; i < keys.length; i++) {
+            if (stored[keys[i]]) {
+                parts.push('utm_' + keys[i] + '=' + encodeURIComponent(stored[keys[i]]));
+            }
+        }
+        return parts.join('&');
+    }
+
+    window.UTM = { parse: parseUTM, getStored: getStoredUTM, inject: injectUTM, appendToForm: appendToForm, toQuery: toQuery };
     window.UTM.parse(); // Parse on page load
 })();
 
@@ -196,13 +222,15 @@ var si = 0,
                 yearlySave.style.display = "block";
                 var buyBtn = document.getElementById("orderBuyBtn");
                 var loc = document.getElementById("orderServerLocation").value;
+                var utmQuery = UTM.toQuery();
                 buyBtn.href =
                     "/3/" +
                     price.toFixed(2) +
                     "/4/" +
                     encodeURIComponent(plan) +
                     "?location=" +
-                    encodeURIComponent(loc);
+                    encodeURIComponent(loc) +
+                    (utmQuery ? "&" + utmQuery : "");
                 widget.style.display = "flex";
                 orderPopupShown = true;
             }
@@ -233,13 +261,15 @@ var si = 0,
                         .trim();
                     var price = parseFloat(priceText);
                     var loc = this.value;
+                    var utmQuery = UTM.toQuery();
                     document.getElementById("orderBuyBtn").href =
                         "/3/" +
                         price.toFixed(2) +
                         "/4/" +
                         encodeURIComponent(plan) +
                         "?location=" +
-                        encodeURIComponent(loc);
+                        encodeURIComponent(loc) +
+                        (utmQuery ? "&" + utmQuery : "");
                 });
             function applyCoupon() {
                 var input = document.getElementById("orderCouponInput");
@@ -719,6 +749,7 @@ var si = 0,
                 clear.name = 'clear';
                 clear.value = '1';
                 form.appendChild(clear);
+                UTM.appendToForm(form);
                 document.body.appendChild(form);
                 form.submit();
                 document.body.removeChild(form);