How Amazon Affiliate Links Work
The tag in the URL, the attribution window, and why the same link can earn differently depending on where it's clicked — the full mechanics.
The tag is the whole mechanism
Every Amazon affiliate link carries a tag= parameter identifying your Associates account. When someone clicks it and buys within the attribution window, Amazon credits that sale to your tag. Strip the tag, and the exact same product page earns nothing — the tag isn't cosmetic, it's the entire tracking mechanism.
The attribution window, precisely
Amazon's session-based tracking works like this: clicking your link starts a session that lasts until the first of three things happens — 24 hours elapse, an order is placed, or the visitor clicks through a different Associate's link instead. If they buy within that 24-hour session, you're credited.
There's an important extension: if a visitor adds a product to their cart during that 24-hour session, you still get credit if they complete the purchase within 89 days of the original click — the item just has to have been added to the cart within the initial 24 hours, not added later. This is a narrower rule than a blanket "89-day cookie," and it's worth being precise about — see Amazon's affiliate cookie duration explained for the full breakdown.
Separately, Amazon's Operating Agreement requires a purchased product to actually be shipped (or streamed/downloaded, for digital goods) and paid for within 180 days for the commission to be paid out at all — a fulfillment deadline, distinct from the attribution window itself.
Per-marketplace separation
Amazon Associates isn't one global program — amazon.com, amazon.ca, amazon.co.uk, and every other marketplace run their own separate Associates programs, each with its own signup and its own tracking ID. A US tag earns nothing on a sale through amazon.ca, even for the identical product. See Amazon.com vs Amazon.ca for what this means in practice.
Commission rates vary by category
Amazon doesn't pay one flat percentage — the rate depends on the product category, from around 10% for some categories down to a flat per-item amount or 0% for others. See the full current rate breakdown.
Why a link might not convert despite all of this working correctly
Even with a correctly tagged link inside the attribution window, a sale might not happen for reasons unrelated to the mechanism itself — price sensitivity, product fit, or simply an audience that wasn't ready to buy. See why your Amazon affiliate links aren't converting for the most common actual causes.