Cashback portals have a fairly predictable base rate for each retailer they partner with. What's less documented is that those rates go up periodically — sometimes to double or triple the normal percentage — during bonus windows that last anywhere from 24 hours to a week.
These windows exist because retailers pay portals for traffic during specific promotional periods, usually tied to their own sale events. The portal passes some of that elevated commission back to users as a bonus rate. The catch is that these windows are often not prominently advertised — you need to be looking for them or have a system for catching them.
What a bonus window actually looks like
The most common format is a flat multiplier: "earn 3x cashback this weekend" or a specific elevated percentage for a named retailer. Less common but higher-value are category-specific bonuses — "electronics at 6% until midnight Thursday" — which can be meaningfully larger than the standard rate.
Dutch cashback networks tend to run their biggest bonus windows around three predictable anchors: the week before national sale events, the start of major retailer clearance cycles (January and July primarily), and opportunistically around competitor promotions when a retailer wants to capture switched shoppers.
How to not miss them
The most reliable method is to check the portal's "promotions" or "bonussen" section before any significant purchase, not as part of your routine browsing. The portal's email alerts for bonus windows are useful but often too slow — by the time the email arrives the 24-hour window may be half-gone.
If you make more than a few meaningful online purchases per month, it's worth bookmarking the bonus pages for the two or three portals you use and checking them before checkout rather than just navigating directly to the retailer. The extra 45 seconds almost always pays off relative to the savings on larger purchases.
The interaction with deal timing
Where this gets interesting is when a genuine deal (real price below 90-day median) coincides with an elevated cashback window. This is why cashback potential is one of our four Deal Score factors — it can upgrade a B deal to an A when the timing aligns. We track portal bonus windows for major Dutch retailers and note when they overlap with deals we're covering.
The stacking guide covers the mechanics of combining portals with other savings methods without voiding your cashback claim — a separate topic but related to getting full value here.