What is GAM Passback Tag and When to Use it?

Updated on: March 29, 2024
Is passback a better strategy for monetizing your remnant inventories? But first, what are passback tags?

Trying to generate Google Ad Manager passback tags? Here’s the passback tutorial that will help you to understand the basics of passback and how to generate the passback tags.

Despite working with multiple ad networks, you might end up with unfilled impressions. Let’s assume you work with an ad network to monetize a specific section/category of your website (publishers experimented with different ad networks to figure out the ideal networks for each category of their site). If the selected ad network can only offer a CPM rate of $2 but your price floor is higher than the bid, you can’t deliver an ad to the user and essentially, leaving money on the table. 

To put it simply, passback was introduced to minimize the unfilled impressions and increase the ad fill rate. This directly converts into ad revenue for publishers like you. Let’s start with a simple question. 

What is a Google Ad Manager Passback Tag?

DFP passback is a process that enables the publisher’s ad server (i.e., Google Ad Manager) to fill remnant ad inventories by passing down the ad requests to multiple ad networks. Even if there’s no eligible ad, the publisher’s in-house ad will be served by the ad server. Passback tags are basically JavaScript codes just like other ad tags. The only difference that exists is in the way passback tags function.

When do you Need a Passback Tag?

If you want to run more than one ad network at the same time and deliver an ad if the primary network returns nothing, then you can enable the GAM passback functionality to fill the remnant ad inventories.

Long answer:

Suppose, you’re trying to monetize some pages of your website. And you reached an ad network A and requested to return an ad for the remnant inventories on the pages. But, network A doesn’t have eligible ads to deliver the expected fill rate. 

Then, you found that network B can return ads for your remnant ad inventories. So, how do you enable ad network B to return an ad for the inventories (that were supposed to be filled by network A but couldn’t)? In this case, to make both ad networks run at the same time and deliver an ad if the primary network returns nothing, ‘passback’ functionality is required to be enabled.

Curious to know how passback tags work? Don’t worry. We’re going to discuss it in a minute.

So, how do passback tags work?

Usually, the passback process includes the following steps:

  1. When a viewer visits a website and loads a page, the browser makes a call to the publisher’s ad server (first-party ad server) using an ad server tag (in our case, it will be a GPT tag with passback functionality enabled). 
  2. The ad server tag returns an ad that consists of a third-party (buyers) ad server tag.
  3. This third-party ad server tag makes a call to the third-party ad server via third-party ad networks and requests to deliver an eligible ad.
  4. If the third-party ad server doesn’t have an ad to deliver, it returns a passback tag to the publisher’s web browser. The browser reads the passback tag and gets to know that it has to call the publisher’s ad server again so that the server starts looking for ads from other ad networks.
  5. Then, the publisher’s ad server tries to reach another third-party ad network and requests to deliver an ad. Again, if the second ad network has no ads, it returns the passback tag to the browser. The process continues until Google Ad Manager reaches out to all the trafficked ad networks. 
  6. At last, if the publisher’s ad server couldn’t get any ads from the ad networks, it displays in-house ads of the publisher. 

Tip: You can also advertise your partner sites by trafficking their ad creatives as house ads.

So, that’s how the whole process of passback happens. But, do you know how to define and generate a passback tag in an ad server? If not, let’s understand this in detail. 

How to generate passback tags in Google Ad Manager (Google DFP)?

Google’s ad server offers a number of advantages to publishers and one of them is defining the Google publisher tag (GPT) as a passback tag.  

  1. Log in to your Google Ad Manager account.
  2. Select the Inventory tab.
  3. Select all the ad units for which you want to create passback tags for.
  4. Then, click on the Generate tags.
  5. After this, go to the Tag type drop-down menu and select Google Publisher Tag (Asynchronous).
  6. Then, click on Continue and select Tag Options. After selecting Tag Options, select Create Passback Tag and then Continue. That’s it. 

Now, all you have to do is – set the passback ad tags live on your website, and you’re ready to go. 

Although passback helps in selling your remnant ad inventories, it may not be always helpful. While setting up passback, you may come across a situation when none of the ad networks is eligible to return ads. And that’s one of the reasons many publishers are going for header bidding – which replaces the traditional waterfall method. 

So, if you have remnant inventories, we suggest you implement header bidding and move beyond the waterfall or passback method. Got confused about which one to choose? Don’t be. We’re going to help you pick the best one.

What to Choose Passback or Header Bidding?

Indeed, the Google Ad Manager passback tag can improve your fill rate, But it doesn’t mean that you can have a 100% ad fill rate, since your impressions are passed from one ad network to another, which in turn, undermines the value of your inventory. But header bidding is a method through which you can sell your ad inventories by allowing multiple ad networks or ad exchanges to bid for the ad inventories in real-time.

What happens in header bidding is – you reach multiple ad networks or exchanges to let them know about your remnant ad impressions. Then, these ad networks call the demand-side platforms to bid for the inventories, and whoever bids the highest returns the ads. 

Unlike the passback method where ad networks are prioritized on the basis of their historical data (CPM rates, buying volume, etc.), header bidding enables different platforms (ad networks, ad exchanges, etc.) to compete in real-time and sell your ad inventories. Here, all ad networks or exchanges get an equal opportunity to participate and bid for the impressions. This means better competition and increased revenue. 

 What’s Next?

For a publisher, monetizing the unsold inventories is a major concern. Passback can help you resolve it to a certain extent but you can never be assured that all the inventories will be filled. To make sure that no inventories remain unfilled, a publisher needs to leverage header bidding. What if you aren’t eligible to run header bidding yet? Simple, run waterfall auctions, but make sure to limit the number of ad networks to 4. Why? The more the networks, the higher the page latency.  

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