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Technology and tracking

Sub-ID tracking

Also called SubID, sub-ID parameter, clickref, sid.

Short answer

Sub-ID tracking lets an affiliate attach their own labels to an affiliate link – for example campaign, placement or ad – which follow the click all the way to the conversion. In the reports, the affiliate can then see exactly which source created each sale.

Definition of Sub-ID tracking.

A sub-ID is a parameter the affiliate adds to their tracking link themselves – for example subid=newsletter-august. The value is stored together with the click, and when a conversion is attributed to the click, the sub-ID comes along into the reports. The network does not interpret the content; the label is the affiliate's own and means exactly what the affiliate has decided.

The purpose is to split performance under the same link. One affiliate account can cover a newsletter, 3 articles and 2 ad channels – without sub-IDs, everything appears as one pool. With sub-IDs, the affiliate can see that the price article converts while the banners do not, and move the effort accordingly. It is the data foundation for any optimisation on the affiliate side.

Sub-IDs are often confused with UTM parameters, but they solve different problems: UTMs are read by the affiliate's own analytics tool and stop at the page view, while the sub-ID travels through the tracking system and lands on the conversion itself. A serious setup uses both – UTM for traffic analysis, sub-ID for commission data.

A usable sub-ID taxonomy

Decide the structure before you put links out. A simple model is channel-placement-variant, for example nl-top-a for the newsletter's top placement in variant A. Keep the number of unique values down – 10–20 recurring labels give data that can be compared, whereas hundreds of one-off values fragment everything into noise.

Avoid personal data. A sub-ID ends up in reports, exports and log files, and an email address or a customer ID in the parameter turns tracking data into personal data, with everything that requires under GDPR. Use anonymous labels for sources – never identifiers for people.

Sub-ID vs. UTM parameters

AspectSub-IDUTM parameters
Read bythe affiliate network's trackingyour own analytics tool
Follows the conversionyes – stored on the click and shown with the saleno – stops at the visit to your site
Formatfree – the affiliate defines the values5 standard fields (source, medium, campaign, term, content)
Question answeredwhich placement earned the commissionwhere did the traffic to my site come from

Use UTM to understand your own traffic – use sub-ID when you want to know which source ended in commission.

How it goes wrong

  • 01

    Personal data in the parameter

    Emails, usernames and customer IDs never belong in a sub-ID. The value is stored and shown in reports, and it therefore falls under GDPR – with requirements for a legal basis, deletion and access that no one wants to be liable for in tracking data.

  • 02

    Too many one-off values

    A new sub-ID per day or per post sounds detailed, but leaves 200 labels with 3 clicks each – too little to conclude anything. Recurring labels across time are what make comparison possible.

  • 03

    Labels that are never read

    Sub-IDs without a fixed reporting routine are wasted discipline. Decide which question each label should answer and look at the figures at a fixed cadence – otherwise the taxonomy decays within 14 days.

Frequently asked questions

What is a sub-ID in affiliate marketing?

A sub-ID is a label the affiliate puts on their tracking link to tell sources apart – for example campaign, placement or ad. The label is stored with the click and shown in the reports together with the conversions the click leads to.

What is the difference between sub-ID and UTM parameters?

UTM parameters are read by your own analytics tool and describe the visit to your site. The sub-ID is read by the affiliate network's tracking and follows along all the way to the conversion. UTM shows traffic – sub-ID shows which source earned commission.

Can I put customer data in a sub-ID?

No. Sub-IDs are stored in reports and log files, and personal data in the parameter turns the whole tracking chain into processing of personal data under GDPR. Use anonymous source labels such as nl-top or article-price – never emails or customer IDs.

How many sub-IDs should I use?

Few enough to compare. A fixed taxonomy of 10–20 recurring labels – for example channel plus placement – gives data that can be read over time. Hundreds of one-off values fragment the figures so that no single sub-ID reaches a measurable volume.

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