General information, not legal advice. This chapter summarises published regulator guidance in plain language. For a decision that matters, read the cited documents and talk to a qualified adviser.
Two audiences, two jobs
An affiliate link has two audiences. Readers need to know that the publisher is paid if they buy; earlier chapters cover that. Search engines need to know that the link was placed because of a payment, so they do not treat it as an independent recommendation. These are different jobs, done in different ways, and doing one does not do the other.
This chapter is about the second job. It relies on Google's own documentation, because only a search engine can say how it treats signals on its own systems. Other search engines may treat link attributes differently.
The three rel values
HTML links can carry a rel attribute that describes the relationship between the page and the page it links to. Google's page "Qualify your outbound links to Google" describes three values for this purpose:
| Value | Use it for |
|---|---|
rel="sponsored" | Links that are advertisements or paid placements, that is, paid links. |
rel="ugc" | Links inside user-generated content, such as comments and forum posts. |
rel="nofollow" | Other links you do not want associated with your site or crawled from it, where the other values do not fit. |
Google's page also explains that more than one value can be combined in the same attribute, separated by spaces or commas, for example rel="ugc nofollow". For paid links it prefers sponsored, and says that nofollow is also acceptable. Google treats these values as hints about how to handle the link.
Why paid links should be qualified
Search engines use links between sites as one of many signals about which pages are useful. A link that someone was paid to place is not an independent vote of confidence, so treating it as one would distort results.
Google's "Spam policies for Google web search" describe link spam, including buying or selling links in order to influence rankings. The policy gives examples such as exchanging money, goods or services for links, or for posts that contain links. It also says that buying and selling links for ordinary advertising and sponsorship is a normal part of the web, and is not a violation as long as such links are qualified with rel="sponsored" or rel="nofollow". In other words, the problem is not the payment; it is a paid link presented to the search engine as if it were unpaid.
Applying this to affiliate links
An affiliate link is a link the publisher is paid for: commission is earned when readers follow it and buy. That puts it in the paid category Google's documentation describes, and the most straightforward reading is to qualify affiliate links with rel="sponsored". Many affiliate links pass through a network's tracking address before reaching the merchant, but that does not change their nature, and qualifying the link on your page is still the clear course.
Example markup (invented, for illustration)
<a href="https://shop.example/product?ref=abc123" rel="sponsored">See the current price</a>
The domain shop.example is a reserved example name, not a real shop. If the link also opens in a new tab, values such as noopener can sit alongside sponsored in the same attribute.
Putting it into practice
- Set it in templates, not by hand. If affiliate links are produced by a template, a shortcode, a plug-in or a link-management tool, set the attribute there so every affiliate link gets it automatically.
- Check your link redirects. Some sites route affiliate links through a short address on their own domain. The link on the page is still a paid link and should still carry the qualifier.
- Do not qualify ordinary editorial links. A link to a source you are citing, with no payment involved, is an editorial link and does not need
sponsored. Marking everything as paid hides the difference. - Remember gifts. Google's link spam examples include giving free products in return for a post that contains a link. Where a link exists because of that kind of arrangement, treat it as paid.
- Audit old content. Older posts may predate your current approach. A periodic check of pages with affiliate links catches missing attributes and missing reader disclosures at the same time.
Thin affiliate pages
Google's spam policies also describe "thin affiliation": pages that carry affiliate links but add little or nothing beyond what the merchant already provides, for example product descriptions and reviews copied straight from the merchant's site with no original content. The policy makes clear that being an affiliate is not the problem. Affiliate pages that add real value, such as original testing, comparison or expertise, are not what it targets.
This connects to the reader side of the handbook. A page that exists only to pass readers to a merchant, with copied content and no honest assessment, is unhelpful to readers and to search engines alike. Chapter 06 looks at what makes a review genuinely useful.
An attribute is not a disclosure
The rel attribute is in the page code. Readers do not see it, and most would not know what it meant if they did. It tells a search engine something; it tells readers nothing.
The FTC's FAQ and the ASA's guidance are about what readers see and understand. A page whose affiliate links all carry rel="sponsored" but which has no visible disclosure has dealt with search engines and left readers uninformed. The reverse is also incomplete: a clear disclosure with unqualified links informs readers but leaves the search engine to treat paid links as editorial ones.
In one line
Qualify affiliate links for search engines with rel="sponsored", and disclose them to people in plain words they can see. You need both.