ads.txt for AdSense: Setup, Exact Format and Common Errors

For AdSense, ads.txt is a plain text file at https://yourdomain.com/ads.txt containing one line: google.com, pub-0000000000000000, DIRECT, f08c47fec0942fa0, with your own 16-digit publisher ID. Google says the file is "not mandatory, but it's highly recommended". There is one catch that matters more than the recommendation: if your domain has an ads.txt file and it does not list you, Google-served ads are not allowed there. So either add the correct line or make sure no file exists.

What ads.txt does and whether you need it

ads.txt ("Authorized Digital Sellers") is an IAB Tech Lab standard that lets a site owner publicly list which companies may sell its ad space. Buyers check it to avoid paying for counterfeit inventory.

For AdSense it has three roles:

1. Authorising Google. Advertisers that check ads.txt see that Google may sell your inventory.
2. One of three ways to verify your site. The AdSense code snippet, the google-adsense-account meta tag and an ads.txt line are all accepted (Connect your site).
3. A hard rule once it exists. Google Publisher Policies say you must not "place Google-served ads on a domain that uses ads.txt where you are not included as an authorized seller" (Dishonest declarations and ads.txt).

That last point is why a half-finished file is worse than none. A theme or plugin that creates an empty ads.txt, or a file left over from another network, can block AdSense on its own.

The exact line for AdSense

From the AdSense ads.txt guide:

google.com, pub-1234567890123456, DIRECT, f08c47fec0942fa0

Field	Value	Notes
1. Ad system domain	google.com	Always google.com for AdSense, not googlesyndication.com
2. Publisher ID	pub- + 16 digits	Only the pub- prefix. Google: "Delete the product-specific prefix (for example, ca- or ca-video-)" (Ads.txt FAQs)
3. Relationship	DIRECT	You own the account. RESELLER for your own ID is wrong
4. Certification authority ID	f08c47fec0942fa0	Google's TAG ID. Optional in the IAB spec, but include it

Find your publisher ID in AdSense under Account > Settings > Account information. It appears in your ad code as ca-pub-1234567890123456; in ads.txt you drop the ca-.

If you run other networks, each adds its own lines. A file for a site using AdSense and one other network might look like this:

# ads.txt for example.com
google.com, pub-1234567890123456, DIRECT, f08c47fec0942fa0
examplenetwork.com, 98765, DIRECT
contact=ads@example.com

Lines starting with # are comments. contact= and ownerdomain= are optional variables from the IAB ads.txt 1.1 spec, which lists OWNERDOMAIN as recommended.

Where the file must live

The rules are strict and come from Ensure ads.txt can be crawled:

• At the root of the registrable domain, at the path /ads.txt. Not in a folder, not /ads.txt/, not /wp-content/ads.txt.
• On the root domain, not only on www. "An ads.txt file on www.domain.com/ads.txt will only be crawled if domain.com/ads.txt redirects to it."
• Reachable over HTTP and HTTPS, directly or by redirect.
• Returning HTTP 200. A 404 means Google treats the file as missing; an HTML "page not found" served with 200 is a soft 404 and is also a problem.
• Not blocked by robots.txt. Watch for prefix rules: Disallow: /ads also blocks /ads.txt.
• Plain text, ideally with Content-Type: text/plain and UTF-8 encoding.

Subdomains with their own ad setup are declared from the root file with subdomain=blog.example.com.

How to add it on common platforms

WordPress

The simplest way is to upload a file named ads.txt to the WordPress root folder (the one containing wp-config.php) by FTP or your host's file manager. Alternatively, use a dedicated ads.txt plugin, which serves the file through WordPress. Do not use both: a physical file usually wins, and you will edit the wrong one. After a caching or security plugin update, recheck that /ads.txt still returns plain text.

Blogger

Go to Settings > Monetization, turn on "Enable custom ads.txt", and paste the line. For blogs that monetise through Blogger, Blogger can handle the AdSense entry itself; use the custom option only if you need to add or fix lines.

Static hosts (Netlify, Vercel, Cloudflare Pages, GitHub Pages)

Put ads.txt in the folder that is published as the site root (often public/ or static/). Make sure your framework does not rewrite unknown paths to index.html, which would turn /ads.txt into an HTML page.

Hosted shops and site builders

Some builders let you add ads.txt in the dashboard; others do not allow root files at all. Google supports "a single HTTP redirect to a destination outside the original root domain", so a platform redirect from /ads.txt to a hosted text file can work. If the builder cannot serve the file at all, rely on the meta tag or code snippet for verification instead.

Common errors and fixes

Symptom	Cause	Fix
AdSense shows ads.txt "Not found"	File missing on the root domain, or only on www without a redirect	Serve it at https://example.com/ads.txt
"Unauthorized" or earnings at risk warning	Wrong or missing publisher ID line	Copy the exact line with your own pub- ID
Line ignored	ca-pub- used instead of pub-, or 15/17 digits	Use pub- plus exactly 16 digits
File parsed as garbage	Written in a word processor: smart quotes, non-breaking spaces, a BOM	Recreate it in a plain text editor
Browser shows a styled page	Framework or CMS returns HTML for unknown paths	Serve a real static file
Google cannot read it	Disallow: /ads or similar in robots.txt	Allow /ads.txt
Ads blocked on a site that used to work	A new network or plugin replaced the file without the Google line	Merge lines into one file

Check that it works

curl -sI https://example.com/ads.txt
curl -sI http://example.com/ads.txt
curl -s https://example.com/ads.txt

You want 200 on both schemes (directly or after a redirect), a text/plain content type and your Google line in the body. In AdSense, the Sites page shows the ads.txt status. Updates are not instant: Google's crawler needs to refetch the file, which can take a few days.

For crawler rules that affect ads.txt, see the robots.txt guide. The approval checklist lists ads.txt alongside the other verification steps, and our methodology explains exactly which ads.txt checks we run.

Validate your ads.txt for free

A free scan fetches your ads.txt over both schemes, parses each line, compares the publisher ID with your ad code and flags formatting problems. Run a free scan.

FAQ

Do I need ads.txt to get AdSense approval?

No. It is optional and one of three verification methods. If you create one, it must include your Google line.

Can I put ads.txt on a subdomain?

Google reads the file at the root domain. For subdomains with separate ad setups, reference them from the root file with a subdomain= line.

How long does Google take to see a new ads.txt?

Usually a few days, because the crawler has to refetch it. Make sure it returns 200 and plain text, then wait before changing anything else.

I removed AdSense from a site. Should I delete the Google line?

Yes, if you no longer have an account relationship there. ads.txt should accurately reflect who may sell your inventory.