I don't raise rates for families already in care but sometimes set a new rate for families that are starting. I explain it with the idea that as long as you stay in care your rate never changes. I have families at three different rates right now and the lowest ones will be the family leaving this summer for child to start school and the new family coming in will be paying slightly higher than the family that started 2 years ago.

If for some reason I was doing an across the board raise I would do it in newsletter form, give them a couple months notice and an explanation as to why the increase is necessary. I would also add something about anyone that finds that this change presents a hardship to speak to me. Ideally that allows you to know who isn't happy with the decision and who might decide to look for care elsewhere so it gives you a heads up.