I think it's the wages you report on Form 941 but NOT including wages you use for another benefit, such as PPP forgiveness. I don't think it kicks in until you're filing 2Q Forms 941, so we have lots of time to continue getting clarifications that are arriving almost daily. I'm sure you know as much as anyone else; but if you're unsure, you could find a good payroll company to work with your payroll clients. (I got rid of all my payroll clients to places like Paychex, so I don't have to learn the finer detail of this one!)