---
title: "Set up passback on a Code or Template banner"
description: "Let a creative tell the Epom tag it has nothing to show — tick Enable passback functionality, save, copy the Banner passback code into the tag's no-ad path — and the permission and AJAX domain it needs."
type: "howto"
audience: [network-manager]
keywords: [passback, banner passback code, enable passback functionality, no ad, fall through, AJAX invocation code, passback domain, third-party tag empty]
ui_path: "Account → Advertisers → campaign → Add new banner"
---

Fetch the complete documentation index at: https://epom.com/ad-server/docs/llms.txt. Use this file to discover all available pages before exploring further. Append .md to any documentation page URL to get its markdown version.

# Set up passback on a Code or Template banner

Passback lets a creative tell the Epom tag "I have nothing to show", so the tag can fall through
to the next line of demand instead of leaving a blank. It is a per-banner switch on HTML Code
banners (Site, Non-standard and Mobile site placements) and Template banners (Site and
Non-standard), and it produces a snippet you paste into the creative's no-ad path. The banner
types themselves are on [HTML code and Template banners](https://epom.com/ad-server/docs/guides/advertising/banner-html-and-template.md).

**Example.** Northwind Media's 300×250 ad-network tag sometimes has no ad. With **Enable passback
functionality** ticked on the HTML Code banner and the **Banner passback code** pasted into the
tag's no-ad path, the slot is handed back and the next line of demand fills it.

## Typical scenarios

| You want | Set | Where |
|---|---|---|
| A third-party tag's slot to fall through when the tag is empty | Tick **Enable passback functionality**, save, reopen, paste the **Banner passback code** into the tag's no-ad path | Needs the AJAX invocation-code permission and a configured AJAX domain |
| The snippet for a page served from your second AJAX domain | Pick that domain in the **Domain** list above the block before copying | the saved banner |
| A chain of fallbacks on the placement rather than in the creative | [Daisy chaining and passback](https://epom.com/ad-server/docs/guides/delivery/daisy-chaining-passback.md) | the placement |

## Step by step

### Passback

Passback lets a creative tell the Epom tag "I have nothing to show", so the tag can fall through
to the next line of demand.

1. Tick **Enable passback functionality** above **Banner type** and **Save**. The checkbox is
   shown only to a role holding the AJAX invocation-code permission for the banner's placement
   type (Standard, Non-standard or Mobile site), and only once your network has an AJAX
   invocation-code domain to build the snippet from.
2. Reopen the banner: a **Banner passback code** block appears below the checkbox. With several
   AJAX invocation-code domains, pick the one your page's tag is served from in the **Domain**
   list above the block; the choice is not saved, so the first domain shows each time.
3. Paste the snippet into your creative on the path where it decides not to render. It posts a
   message up the frame chain that the Epom AJAX tag picks up.

Placement-side fallback chains are a different feature — see
[Daisy chaining and passback](https://epom.com/ad-server/docs/guides/delivery/daisy-chaining-passback.md).

## Caveats and exceptions

**The passback code block only exists on a saved banner.** Enable → Save → the block appears;
there is nothing to copy while creating. If the network has no AJAX invocation-code domain, the
checkbox is not offered at all — ask Epom support or your account manager to set up an AJAX
invocation code. A banner that already has passback on keeps the checkbox so you can turn it off.

The caveats that apply to the banner types — who can do this, the Ad unit rules, the type
switch — are on [HTML code and Template banners](https://epom.com/ad-server/docs/guides/advertising/banner-html-and-template.md#caveats-and-exceptions).

## Not working?

| Symptom | Check | Where |
|---|---|---|
| No **Enable passback functionality** checkbox | Role lacks the AJAX invocation-code permission for this placement type, the network has no AJAX invocation-code domain, or the placement is Video / Application / Mobile-site Template | Admin → Users & access → User roles & permissions; Epom support for the AJAX domain |
| No **Banner passback code** block after ticking | The banner is not saved yet | Save, then reopen the banner |
| The passback snippet points at the wrong domain | The **Domain** list resets to the first entry on every open | Pick the page's tag domain again before copying |

The rest of the list is on [HTML code and Template banners](https://epom.com/ad-server/docs/guides/advertising/banner-html-and-template.md#not-working).

## Reference

Which placements offer the checkbox for each type:
[What each placement asks for](https://epom.com/ad-server/docs/guides/advertising/banner-html-and-template.md#what-each-placement-asks-for); the
field itself is in [Options and fields](https://epom.com/ad-server/docs/guides/advertising/banner-html-and-template.md#options-and-fields).

## Related

- [HTML code and Template banners](https://epom.com/ad-server/docs/guides/advertising/banner-html-and-template.md)
- [HTML Code banners](https://epom.com/ad-server/docs/guides/advertising/banner-html-and-template-html-code.md)
- [Template banners](https://epom.com/ad-server/docs/guides/advertising/banner-html-and-template-template.md)
- [Daisy chaining and passback](https://epom.com/ad-server/docs/guides/delivery/daisy-chaining-passback.md)
- [Google passback tags](https://epom.com/ad-server/docs/troubleshooting/google-passback-tags.md)