My mom is an accountant and she always does my taxes and I have never given out my sin number.She told me I don't have to. Like the a previous poster if someone was audited and absolutely needed it then I would provide it. I am not comfortable just handing it out to anyone, None of my parents have ever asked. I have given my daycare a business name but it does not need to be registered since I don't make enough. So on my receipt it says my daycare name and address and then down below how much the daycare service was and for how long and at the bottom it just says Paid in full thank you. When I was on the other end and was a parent, my DCP didn't put hers down either.