I give receipts in January and July, for the preceding 6 months. If a client was paying in cash, and they requested receipts for every payment, then I would likely agree to it. But I STRONGLY encourage people to use email transfers. They have records, I have records.
I know it's not what you were asking; but I personally know of MANY providers who are working "under the table". I do think it's a very short term perspective, due to what Reggio mentioned. It doesn't really bother me, though, since I feel like it is only to their detriment in the end.
I wanted to claim my income because I wanted to "exist" as far as banks, etc are concerned. We know that we will be moving in the next 5 years, so when it comes time to go in for that mortgage, they don't just take your word that you are a daycare provider earning x-amount of dollars annually. They need to see those Notice of Assessments from the last 2-3 years, sometimes longer!! For tax purposes, there are enough available deductions and write offs that I am not worried about paying too much in taxes.