Cash back shopping portals operate on affiliate commission agreements with retailers: when a shopper clicks through the portal to a retailer's site and completes a purchase, the retailer pays the portal a commission, a portion of which the portal shares back with the shopper as cash back.
Critically, this portal-level cash back is entirely separate from -- and stacks on top of -- whatever cash back rate the shopper's credit card itself pays on the same purchase, since the portal's commission and the card's reward program operate through completely different mechanisms.
This means a purchase paid for through a cash back portal using a 2% flat-rate card can realistically earn a combined 4-6% total return once both the portal's share and the card's cash back are counted, compared to 2% from the card alone.
Portal payouts typically carry a delay of 60 to 90 days, because the portal waits for the retailer's return-and-refund window to close before finalizing the commission and crediting the shopper's account -- unlike card-issued cash back, which usually posts within one to two billing cycles.
The main friction with portals is remembering to click through before every applicable purchase, since forgetting to start the shopping session through the portal forfeits that layer of cash back entirely, even though the card's own cash back still applies normally.
Continue reading: Business Cash Back Cards: What No One Tells You · Try the free Cash Back Mastery Simulator
No, they are free to use -- the portal's revenue comes from the retailer's affiliate commission, not from the shopper.
Portals typically wait out the retailer's return window (60-90 days) before finalizing the commission, to avoid paying out on orders that get refunded.