What is the minimum percentage (of full-time) employment required to be eligible for the mandatory German public health insurance? Is there any wage rate requirement for that employment? That is, if i need to work at least x% if full-time at y% rate, what are x and y? I realize y is dependent on my job and experience, but is there some kind of a minimum base limit?
The Geringfügigkeitsgrenze is 15 hours of work per week and about 400 € of income per month. That latter amount is different for former West and East German states and slightly increased each year. (To be exact: It's 1/7 of the Bezugsgröße, or 1/6 of it for some cases).
If you are below that border, you are not required to have a public health care and geriatric care insurance. However, you are still eligible. It costs about 200 € per month for these cases. It's common for house wives to opt-in for public health insurance if their husband has private health insurance – their partner plan costs much more, usually.
If your partner has public health insurance, spouse and children are automatically covered.