How to Use Sub IDs in Affiliate Tracking

What a sub ID is (and isn't)

A sub ID is a pass-through value. You append it to your tracking link as a query parameter, the network stores it with the click, and it shows up again next to any conversion that click produces. The network doesn't interpret it. It just carries your label from click to report.

That makes sub IDs different from two things they're often confused with:

• Your affiliate ID identifies you to the network and decides who gets paid. You never change it.
• UTM parameters are read by the advertiser's analytics, not by the network's commission reporting. They help the brand, not your payout reports.

Sub IDs are for your analysis. On some platforms they're private; on others one slot is shared with the advertiser. Knowing which is which matters, as you'll see below. For the wider mechanics of how a click becomes a credited sale, see how affiliate tracking works.

How sub IDs flow through the system

The path is the same on almost every network:

1. 01A visitor clicks your link, which carries your values, for example sub1=email&sub2=oct-launch.
2. 02The network's tracking server logs the click with those values attached and redirects to the advertiser.
3. 03If the visitor converts inside the attribution window, the conversion is matched to the original click.
4. 04Your conversion report (or a postback to your tracker) returns the sub ID values alongside the commission.

That last step is why sub IDs are essential for paid traffic. Media buyers usually pass their tracker's click ID into one sub ID slot so the network can send it back in a server-to-server postback, which ties revenue to the exact ad, keyword and placement. If you haven't set that up yet, our explainer on pixel vs postback tracking covers the difference.

Sub ID parameters by network

Every network names the parameter differently, and the limits vary. This table summarises each network's own help documentation; check your dashboard's link builder before going live, because platforms update these over time.

Two takeaways. First, single-slot networks (CJ, ShareASale, ClickBank, Rakuten) force you to pack several dimensions into one string, so your naming convention has to be parseable. Second, shared slots like Impact's sharedid and Awin's first ClickRef are visible to the advertiser, so keep anything commercially sensitive out of them.

A naming system that survives six months

The best sub ID scheme is boring, consistent and machine-readable. Here is a convention that works on both multi-slot and single-slot networks.

Pick a fixed order of dimensions. For most publishers that's:

1. 01Source or campaign: seo, email, yt, fb, nl-oct
2. 02Creative or placement: review-table, cta-top, banner-300, video-desc
3. 03Geo: two-letter country code like us, gb, de
4. 04Device: m or d
5. 05Page or ad ID: a short slug or numeric ID

On multi-slot networks, give each dimension its own slot and keep the mapping identical everywhere. For example, on MaxBounty you might use s1=campaign, s2=tracker click ID, s3=creative, s4=geo, s5=device. On Impact, subId1=campaign, subId2=creative, subId3=page.

On single-slot networks, join the dimensions with a delimiter, always in the same order. A value like email_nl-oct_cta-top_us_m can be split back into columns in a spreadsheet in one step. Hyphens inside values and underscores between them is a simple rule that keeps parsing clean.

Keep a dictionary. A one-page sheet listing every code and what it means saves you when you come back to a report in three months and can't remember what cta2b was.

Worked examples

A content publisher tagging a review page:

• ShareASale: ...&afftrack=seo_best-crm-review_table-row1_us
• CJ: ...?sid=seo_best-crm-review_table-row1_us
• Awin: ...&clickref=seo&clickref2=best-crm-review&clickref3=table-row1&clickref4=us

A media buyer on a CPA offer, passing a tracker click ID:

• MaxBounty: ...&s1=fb-lookalike&s2={clickid}&s3=video-a&s4=ca&s5=m

In each case, you can filter the network report by creative or geo and compare EPC directly. Our guide on what EPC means shows how to read that comparison.

Turning sub ID data into decisions

Tagging is only half the job. The payoff comes from reading the report the same way every time. Export conversions with sub ID columns, split any packed single-slot values into separate columns, and look at each dimension on its own before combining them.

Give each test enough clicks to mean something before acting. A placement with a handful of clicks and one sale hasn't proven anything yet; wait for a meaningful sample, then compare.

Where to start

These networks all document sub ID support in their link tools, and between them cover content, brand and CPA work.

Common mistakes

• Putting personal data in a sub ID. Emails, names or phone numbers don't belong in a tracking parameter. CJ's documentation prohibits it outright, and it's a privacy risk on any network.
• Changing the order halfway through. If s3 means creative in September and geo in October, your history is unusable.
• Using illegal characters. Spaces, &, #, quotes and slashes can break links or truncate values. Stick to lowercase letters, numbers, hyphens and underscores.
• Exceeding length limits. Long values get cut off silently, and you won't notice until a report looks wrong.
• Leaking strategy in shared slots. Advertisers can see shared values, so don't put margins, other brands' names or traffic-source secrets there.
• Tagging only some links. Untagged clicks pile up as a blank row that hides the real performance of everything else.

Step-by-step setup

1. 01List the questions you want answered (which page, which email, which country converts best).
2. 02Choose up to five dimensions that answer them and fix their order.
3. 03Write your code dictionary in a shared sheet.
4. 04Check each network's parameter name and character limits in its link builder.
5. 05Rebuild your links with sub IDs, starting with your top ten earning pages or campaigns. For WordPress sites, tracking affiliate links in WordPress covers link managers that make this easier.
6. 06For paid traffic, pass your tracker click ID into one slot and set up a postback.
7. 07After two weeks, export conversion reports by sub ID and cut the placements and geos that drag EPC down.

Affground's verdict

Sub IDs are the cheapest optimisation tool in affiliate marketing. They cost nothing, take an afternoon to set up, and turn a single blended number into decisions you can act on. Pick a fixed order, keep a dictionary, keep personal data out, and treat any shared slot as public.

• Open API for automation and reporting
• Deep linking to individual offers and products
• Ready-made creatives and promotional assets

• Open API for automation and reporting
• Deep linking to individual offers and products
• Dedicated affiliate manager for active partners

• Open API for automation and reporting
• Deep linking to individual offers and products
• Ready-made creatives and promotional assets