Many lenders pay a cash contribution when you take out or move a loan. It's real money, but it comes with a condition: leave within a set period, often a few years, and you may have to pay some or all of it back.
Advisers can also charge a clawback fee if you refinance soon after they arranged your loan. It's only fair if you agreed to it up front, knew how it's calculated, and saw it in any cost comparison. That's the standard we hold ourselves to.
When comparing offers, add the cashback to the interest you'd save, then subtract anything you'd have to repay. The switching calculator does this for you.