In my specific case, I bought 3 new laptops to replace old ones. It is not possible to dispose of the old devices beforehand or to put them away, otherwise the cashback won't work, because you need the serial numbers of the old devices. And the serial numbers of the new units. And the price of the new units. And the invoice number of the new units. Although you also have to send the invoice. The VAT number and the IBAN must also be entered exactly as requested by HP, i.e. without dots, spaces or anything else (it would be too much to ask HP to do a trimming). I lost almost half an hour on this crap for just 3 devices. I have never experienced such a cumbersome cashback procedure before. In future, I will study the conditions for HP cashbacks before I buy.