HI Sonya,
I don’t charge commercial clients a deposit or builders cleans (unless it is a small unknown company).
The only time I will charge a deposit, is on a domestic clean and then I only charge, if I feel they are not likely to pay.
One example, was four weeks ago, I received a call from a couple who where ending their tenancy and where moving to Spain. The clean would take place after their move. My terms for this where, 50% deposit up front and confirmation from their estate agents, that the estate agents would settle the balance (out of their security deposit).
I did not get the clean, but that did not bother me, because I was sure they had every intention of not paying.
Hope this helps.
Andrew