Accountant is a good thing to consider. The way I have been doing a few jobs for the lighting store is they sell the product and send me the name of the client. I contact them, bid the job and then do the work. They then pay the lighting store and the lighting store in turn pays me. The quote I give the customer includes the lighting store's mark up.
The lighting store now wants to have the customer pay me and then I pay the lighting store at the end of the month their mark up.
Question: Is that considered a "kickback" or referal fee? Difference and is it legal?

I certainly don't want to pay the taxes on the "mark up" as my income. So how do we classify this in accounting?

Thanks for your experiences!